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Math.javaAPI DocJava SE 6 API59597Tue Jun 10 00:25:36 BST 2008java.lang

Math

public final class Math extends Object
The class Math contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.

Unlike some of the numeric methods of class StrictMath, all implementations of the equivalent functions of class Math are not defined to return the bit-for-bit same results. This relaxation permits better-performing implementations where strict reproducibility is not required.

By default many of the Math methods simply call the equivalent method in StrictMath for their implementation. Code generators are encouraged to use platform-specific native libraries or microprocessor instructions, where available, to provide higher-performance implementations of Math methods. Such higher-performance implementations still must conform to the specification for Math.

The quality of implementation specifications concern two properties, accuracy of the returned result and monotonicity of the method. Accuracy of the floating-point Math methods is measured in terms of ulps, units in the last place. For a given floating-point format, an ulp of a specific real number value is the distance between the two floating-point values bracketing that numerical value. When discussing the accuracy of a method as a whole rather than at a specific argument, the number of ulps cited is for the worst-case error at any argument. If a method always has an error less than 0.5 ulps, the method always returns the floating-point number nearest the exact result; such a method is correctly rounded. A correctly rounded method is generally the best a floating-point approximation can be; however, it is impractical for many floating-point methods to be correctly rounded. Instead, for the Math class, a larger error bound of 1 or 2 ulps is allowed for certain methods. Informally, with a 1 ulp error bound, when the exact result is a representable number, the exact result should be returned as the computed result; otherwise, either of the two floating-point values which bracket the exact result may be returned. For exact results large in magnitude, one of the endpoints of the bracket may be infinite. Besides accuracy at individual arguments, maintaining proper relations between the method at different arguments is also important. Therefore, most methods with more than 0.5 ulp errors are required to be semi-monotonic: whenever the mathematical function is non-decreasing, so is the floating-point approximation, likewise, whenever the mathematical function is non-increasing, so is the floating-point approximation. Not all approximations that have 1 ulp accuracy will automatically meet the monotonicity requirements.

author
unascribed
author
Joseph D. Darcy
version
1.72, 11/17/05
since
JDK1.0

Fields Summary
public static final double
E
The double value that is closer than any other to e, the base of the natural logarithms.
public static final double
PI
The double value that is closer than any other to pi, the ratio of the circumference of a circle to its diameter.
private static Random
randomNumberGenerator
private static long
negativeZeroFloatBits
private static long
negativeZeroDoubleBits
Constructors Summary
private Math()
Don't let anyone instantiate this class.

Methods Summary
public static doubleIEEEremainder(double f1, double f2)
Computes the remainder operation on two arguments as prescribed by the IEEE 754 standard. The remainder value is mathematically equal to f1 - f2 × n, where n is the mathematical integer closest to the exact mathematical value of the quotient f1/f2, and if two mathematical integers are equally close to f1/f2, then n is the integer that is even. If the remainder is zero, its sign is the same as the sign of the first argument. Special cases:
  • If either argument is NaN, or the first argument is infinite, or the second argument is positive zero or negative zero, then the result is NaN.
  • If the first argument is finite and the second argument is infinite, then the result is the same as the first argument.

param
f1 the dividend.
param
f2 the divisor.
return
the remainder when f1 is divided by f2.

        return StrictMath.IEEEremainder(f1, f2); // delegate to StrictMath
    
public static intabs(int a)
Returns the absolute value of an int value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned.

Note that if the argument is equal to the value of Integer.MIN_VALUE, the most negative representable int value, the result is that same value, which is negative.

param
a the argument whose absolute value is to be determined
return
the absolute value of the argument.
see
java.lang.Integer#MIN_VALUE

	return (a < 0) ? -a : a;
    
public static longabs(long a)
Returns the absolute value of a long value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned.

Note that if the argument is equal to the value of Long.MIN_VALUE, the most negative representable long value, the result is that same value, which is negative.

param
a the argument whose absolute value is to be determined
return
the absolute value of the argument.
see
java.lang.Long#MIN_VALUE

	return (a < 0) ? -a : a;
    
public static floatabs(float a)
Returns the absolute value of a float value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned. Special cases:
  • If the argument is positive zero or negative zero, the result is positive zero.
  • If the argument is infinite, the result is positive infinity.
  • If the argument is NaN, the result is NaN.
In other words, the result is the same as the value of the expression:

Float.intBitsToFloat(0x7fffffff & Float.floatToIntBits(a))

param
a the argument whose absolute value is to be determined
return
the absolute value of the argument.

        return (a <= 0.0F) ? 0.0F - a : a;
    
public static doubleabs(double a)
Returns the absolute value of a double value. If the argument is not negative, the argument is returned. If the argument is negative, the negation of the argument is returned. Special cases:
  • If the argument is positive zero or negative zero, the result is positive zero.
  • If the argument is infinite, the result is positive infinity.
  • If the argument is NaN, the result is NaN.
In other words, the result is the same as the value of the expression:

Double.longBitsToDouble((Double.doubleToLongBits(a)<<1)>>>1)

param
a the argument whose absolute value is to be determined
return
the absolute value of the argument.

        return (a <= 0.0D) ? 0.0D - a : a;
    
public static doubleacos(double a)
Returns the arc cosine of a value; the returned angle is in the range 0.0 through pi. Special case:
  • If the argument is NaN or its absolute value is greater than 1, then the result is NaN.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a the value whose arc cosine is to be returned.
return
the arc cosine of the argument.

	return StrictMath.acos(a); // default impl. delegates to StrictMath
    
public static doubleasin(double a)
Returns the arc sine of a value; the returned angle is in the range -pi/2 through pi/2. Special cases:
  • If the argument is NaN or its absolute value is greater than 1, then the result is NaN.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a the value whose arc sine is to be returned.
return
the arc sine of the argument.

	return StrictMath.asin(a); // default impl. delegates to StrictMath
    
public static doubleatan(double a)
Returns the arc tangent of a value; the returned angle is in the range -pi/2 through pi/2. Special cases:
  • If the argument is NaN, then the result is NaN.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a the value whose arc tangent is to be returned.
return
the arc tangent of the argument.

	return StrictMath.atan(a); // default impl. delegates to StrictMath
    
public static doubleatan2(double y, double x)
Returns the angle theta from the conversion of rectangular coordinates (xy) to polar coordinates (r, theta). This method computes the phase theta by computing an arc tangent of y/x in the range of -pi to pi. Special cases:
  • If either argument is NaN, then the result is NaN.
  • If the first argument is positive zero and the second argument is positive, or the first argument is positive and finite and the second argument is positive infinity, then the result is positive zero.
  • If the first argument is negative zero and the second argument is positive, or the first argument is negative and finite and the second argument is positive infinity, then the result is negative zero.
  • If the first argument is positive zero and the second argument is negative, or the first argument is positive and finite and the second argument is negative infinity, then the result is the double value closest to pi.
  • If the first argument is negative zero and the second argument is negative, or the first argument is negative and finite and the second argument is negative infinity, then the result is the double value closest to -pi.
  • If the first argument is positive and the second argument is positive zero or negative zero, or the first argument is positive infinity and the second argument is finite, then the result is the double value closest to pi/2.
  • If the first argument is negative and the second argument is positive zero or negative zero, or the first argument is negative infinity and the second argument is finite, then the result is the double value closest to -pi/2.
  • If both arguments are positive infinity, then the result is the double value closest to pi/4.
  • If the first argument is positive infinity and the second argument is negative infinity, then the result is the double value closest to 3*pi/4.
  • If the first argument is negative infinity and the second argument is positive infinity, then the result is the double value closest to -pi/4.
  • If both arguments are negative infinity, then the result is the double value closest to -3*pi/4.

The computed result must be within 2 ulps of the exact result. Results must be semi-monotonic.

param
y the ordinate coordinate
param
x the abscissa coordinate
return
the theta component of the point (rtheta) in polar coordinates that corresponds to the point (xy) in Cartesian coordinates.

	return StrictMath.atan2(y, x); // default impl. delegates to StrictMath
    
public static doublecbrt(double a)
Returns the cube root of a double value. For positive finite x, cbrt(-x) == -cbrt(x); that is, the cube root of a negative value is the negative of the cube root of that value's magnitude. Special cases:
  • If the argument is NaN, then the result is NaN.
  • If the argument is infinite, then the result is an infinity with the same sign as the argument.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result.

param
a a value.
return
the cube root of a.
since
1.5

	return StrictMath.cbrt(a);
    
public static doubleceil(double a)
Returns the smallest (closest to negative infinity) double value that is greater than or equal to the argument and is equal to a mathematical integer. Special cases:
  • If the argument value is already equal to a mathematical integer, then the result is the same as the argument.
  • If the argument is NaN or an infinity or positive zero or negative zero, then the result is the same as the argument.
  • If the argument value is less than zero but greater than -1.0, then the result is negative zero.
Note that the value of Math.ceil(x) is exactly the value of -Math.floor(-x).

param
a a value.
return
the smallest (closest to negative infinity) floating-point value that is greater than or equal to the argument and is equal to a mathematical integer.

	return StrictMath.ceil(a); // default impl. delegates to StrictMath
    
public static doublecopySign(double magnitude, double sign)
Returns the first floating-point argument with the sign of the second floating-point argument. Note that unlike the {@link StrictMath#copySign(double, double) StrictMath.copySign} method, this method does not require NaN sign arguments to be treated as positive values; implementations are permitted to treat some NaN arguments as positive and other NaN arguments as negative to allow greater performance.

param
magnitude the parameter providing the magnitude of the result
param
sign the parameter providing the sign of the result
return
a value with the magnitude of magnitude and the sign of sign.
since
1.6

	return sun.misc.FpUtils.rawCopySign(magnitude, sign);
    
public static floatcopySign(float magnitude, float sign)
Returns the first floating-point argument with the sign of the second floating-point argument. Note that unlike the {@link StrictMath#copySign(float, float) StrictMath.copySign} method, this method does not require NaN sign arguments to be treated as positive values; implementations are permitted to treat some NaN arguments as positive and other NaN arguments as negative to allow greater performance.

param
magnitude the parameter providing the magnitude of the result
param
sign the parameter providing the sign of the result
return
a value with the magnitude of magnitude and the sign of sign.
since
1.6

	return sun.misc.FpUtils.rawCopySign(magnitude, sign);
    
public static doublecos(double a)
Returns the trigonometric cosine of an angle. Special cases:
  • If the argument is NaN or an infinity, then the result is NaN.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a an angle, in radians.
return
the cosine of the argument.

	return StrictMath.cos(a); // default impl. delegates to StrictMath
    
public static doublecosh(double x)
Returns the hyperbolic cosine of a double value. The hyperbolic cosine of x is defined to be (ex + e-x)/2 where e is {@linkplain Math#E Euler's number}.

Special cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is infinite, then the result is positive infinity.
  • If the argument is zero, then the result is 1.0.

The computed result must be within 2.5 ulps of the exact result.

param
x The number whose hyperbolic cosine is to be returned.
return
The hyperbolic cosine of x.
since
1.5

	return StrictMath.cosh(x);
    
public static doubleexp(double a)
Returns Euler's number e raised to the power of a double value. Special cases:
  • If the argument is NaN, the result is NaN.
  • If the argument is positive infinity, then the result is positive infinity.
  • If the argument is negative infinity, then the result is positive zero.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a the exponent to raise e to.
return
the value ea, where e is the base of the natural logarithms.

	return StrictMath.exp(a); // default impl. delegates to StrictMath
    
public static doubleexpm1(double x)
Returns ex -1. Note that for values of x near 0, the exact sum of expm1(x) + 1 is much closer to the true result of ex than exp(x).

Special cases:

  • If the argument is NaN, the result is NaN.
  • If the argument is positive infinity, then the result is positive infinity.
  • If the argument is negative infinity, then the result is -1.0.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic. The result of expm1 for any finite input must be greater than or equal to -1.0. Note that once the exact result of ex - 1 is within 1/2 ulp of the limit value -1, -1.0 should be returned.

param
x the exponent to raise e to in the computation of ex -1.
return
the value ex - 1.
since
1.5

	return StrictMath.expm1(x);
    
public static doublefloor(double a)
Returns the largest (closest to positive infinity) double value that is less than or equal to the argument and is equal to a mathematical integer. Special cases:
  • If the argument value is already equal to a mathematical integer, then the result is the same as the argument.
  • If the argument is NaN or an infinity or positive zero or negative zero, then the result is the same as the argument.

param
a a value.
return
the largest (closest to positive infinity) floating-point value that less than or equal to the argument and is equal to a mathematical integer.

	return StrictMath.floor(a); // default impl. delegates to StrictMath
    
public static intgetExponent(float f)
Returns the unbiased exponent used in the representation of a {@code float}. Special cases:
  • If the argument is NaN or infinite, then the result is {@link Float#MAX_EXPONENT} + 1.
  • If the argument is zero or subnormal, then the result is {@link Float#MIN_EXPONENT} -1.

param
f a {@code float} value
return
the unbiased exponent of the argument
since
1.6

	return sun.misc.FpUtils.getExponent(f);
    
public static intgetExponent(double d)
Returns the unbiased exponent used in the representation of a {@code double}. Special cases:
  • If the argument is NaN or infinite, then the result is {@link Double#MAX_EXPONENT} + 1.
  • If the argument is zero or subnormal, then the result is {@link Double#MIN_EXPONENT} -1.

param
d a {@code double} value
return
the unbiased exponent of the argument
since
1.6

	return sun.misc.FpUtils.getExponent(d);
    
public static doublehypot(double x, double y)
Returns sqrt(x2 +y2) without intermediate overflow or underflow.

Special cases:

  • If either argument is infinite, then the result is positive infinity.
  • If either argument is NaN and neither argument is infinite, then the result is NaN.

The computed result must be within 1 ulp of the exact result. If one parameter is held constant, the results must be semi-monotonic in the other parameter.

param
x a value
param
y a value
return
sqrt(x2 +y2) without intermediate overflow or underflow
since
1.5

	return StrictMath.hypot(x, y);
    
private static synchronized voidinitRNG()

        if (randomNumberGenerator == null) 
            randomNumberGenerator = new Random();
    
public static doublelog(double a)
Returns the natural logarithm (base e) of a double value. Special cases:
  • If the argument is NaN or less than zero, then the result is NaN.
  • If the argument is positive infinity, then the result is positive infinity.
  • If the argument is positive zero or negative zero, then the result is negative infinity.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a a value
return
the value ln a, the natural logarithm of a.

	return StrictMath.log(a); // default impl. delegates to StrictMath
    
public static doublelog10(double a)
Returns the base 10 logarithm of a double value. Special cases:
  • If the argument is NaN or less than zero, then the result is NaN.
  • If the argument is positive infinity, then the result is positive infinity.
  • If the argument is positive zero or negative zero, then the result is negative infinity.
  • If the argument is equal to 10n for integer n, then the result is n.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a a value
return
the base 10 logarithm of a.
since
1.5

	return StrictMath.log10(a); // default impl. delegates to StrictMath
    
public static doublelog1p(double x)
Returns the natural logarithm of the sum of the argument and 1. Note that for small values x, the result of log1p(x) is much closer to the true result of ln(1 + x) than the floating-point evaluation of log(1.0+x).

Special cases:

  • If the argument is NaN or less than -1, then the result is NaN.
  • If the argument is positive infinity, then the result is positive infinity.
  • If the argument is negative one, then the result is negative infinity.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
x a value
return
the value ln(x + 1), the natural log of x + 1
since
1.5

	return StrictMath.log1p(x);
    
public static intmax(int a, int b)
Returns the greater of two int values. That is, the result is the argument closer to the value of Integer.MAX_VALUE. If the arguments have the same value, the result is that same value.

param
a an argument.
param
b another argument.
return
the larger of a and b.
see
java.lang.Long#MAX_VALUE

	return (a >= b) ? a : b;
    
public static longmax(long a, long b)
Returns the greater of two long values. That is, the result is the argument closer to the value of Long.MAX_VALUE. If the arguments have the same value, the result is that same value.

param
a an argument.
param
b another argument.
return
the larger of a and b.
see
java.lang.Long#MAX_VALUE

	return (a >= b) ? a : b;
    
public static floatmax(float a, float b)
Returns the greater of two float values. That is, the result is the argument closer to positive infinity. If the arguments have the same value, the result is that same value. If either value is NaN, then the result is NaN. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero. If one argument is positive zero and the other negative zero, the result is positive zero.

param
a an argument.
param
b another argument.
return
the larger of a and b.


                                                                                                             
           
        if (a != a) return a;	// a is NaN
	if ((a == 0.0f) && (b == 0.0f)
	    && (Float.floatToIntBits(a) == negativeZeroFloatBits)) {
	    return b;
	}
	return (a >= b) ? a : b;
    
public static doublemax(double a, double b)
Returns the greater of two double values. That is, the result is the argument closer to positive infinity. If the arguments have the same value, the result is that same value. If either value is NaN, then the result is NaN. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero. If one argument is positive zero and the other negative zero, the result is positive zero.

param
a an argument.
param
b another argument.
return
the larger of a and b.

        if (a != a) return a;	// a is NaN
	if ((a == 0.0d) && (b == 0.0d)
	    && (Double.doubleToLongBits(a) == negativeZeroDoubleBits)) {
	    return b;
	}
	return (a >= b) ? a : b;
    
public static intmin(int a, int b)
Returns the smaller of two int values. That is, the result the argument closer to the value of Integer.MIN_VALUE. If the arguments have the same value, the result is that same value.

param
a an argument.
param
b another argument.
return
the smaller of a and b.
see
java.lang.Long#MIN_VALUE

	return (a <= b) ? a : b;
    
public static longmin(long a, long b)
Returns the smaller of two long values. That is, the result is the argument closer to the value of Long.MIN_VALUE. If the arguments have the same value, the result is that same value.

param
a an argument.
param
b another argument.
return
the smaller of a and b.
see
java.lang.Long#MIN_VALUE

	return (a <= b) ? a : b;
    
public static floatmin(float a, float b)
Returns the smaller of two float values. That is, the result is the value closer to negative infinity. If the arguments have the same value, the result is that same value. If either value is NaN, then the result is NaN. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero. If one argument is positive zero and the other is negative zero, the result is negative zero.

param
a an argument.
param
b another argument.
return
the smaller of a and b.

        if (a != a) return a;	// a is NaN
	if ((a == 0.0f) && (b == 0.0f)
	    && (Float.floatToIntBits(b) == negativeZeroFloatBits)) {
	    return b;
	}
	return (a <= b) ? a : b;
    
public static doublemin(double a, double b)
Returns the smaller of two double values. That is, the result is the value closer to negative infinity. If the arguments have the same value, the result is that same value. If either value is NaN, then the result is NaN. Unlike the numerical comparison operators, this method considers negative zero to be strictly smaller than positive zero. If one argument is positive zero and the other is negative zero, the result is negative zero.

param
a an argument.
param
b another argument.
return
the smaller of a and b.

        if (a != a) return a;	// a is NaN
	if ((a == 0.0d) && (b == 0.0d)
	    && (Double.doubleToLongBits(b) == negativeZeroDoubleBits)) {
	    return b;
	}
	return (a <= b) ? a : b;
    
public static doublenextAfter(double start, double direction)
Returns the floating-point number adjacent to the first argument in the direction of the second argument. If both arguments compare as equal the second argument is returned.

Special cases:

  • If either argument is a NaN, then NaN is returned.
  • If both arguments are signed zeros, {@code direction} is returned unchanged (as implied by the requirement of returning the second argument if the arguments compare as equal).
  • If {@code start} is ±{@link Double#MIN_VALUE} and {@code direction} has a value such that the result should have a smaller magnitude, then a zero with the same sign as {@code start} is returned.
  • If {@code start} is infinite and {@code direction} has a value such that the result should have a smaller magnitude, {@link Double#MAX_VALUE} with the same sign as {@code start} is returned.
  • If {@code start} is equal to ± {@link Double#MAX_VALUE} and {@code direction} has a value such that the result should have a larger magnitude, an infinity with same sign as {@code start} is returned.

param
start starting floating-point value
param
direction value indicating which of {@code start}'s neighbors or {@code start} should be returned
return
The floating-point number adjacent to {@code start} in the direction of {@code direction}.
since
1.6

	return sun.misc.FpUtils.nextAfter(start, direction);
    
public static floatnextAfter(float start, double direction)
Returns the floating-point number adjacent to the first argument in the direction of the second argument. If both arguments compare as equal a value equivalent to the second argument is returned.

Special cases:

  • If either argument is a NaN, then NaN is returned.
  • If both arguments are signed zeros, a value equivalent to {@code direction} is returned.
  • If {@code start} is ±{@link Float#MIN_VALUE} and {@code direction} has a value such that the result should have a smaller magnitude, then a zero with the same sign as {@code start} is returned.
  • If {@code start} is infinite and {@code direction} has a value such that the result should have a smaller magnitude, {@link Float#MAX_VALUE} with the same sign as {@code start} is returned.
  • If {@code start} is equal to ± {@link Float#MAX_VALUE} and {@code direction} has a value such that the result should have a larger magnitude, an infinity with same sign as {@code start} is returned.

param
start starting floating-point value
param
direction value indicating which of {@code start}'s neighbors or {@code start} should be returned
return
The floating-point number adjacent to {@code start} in the direction of {@code direction}.
since
1.6

	return sun.misc.FpUtils.nextAfter(start, direction);
    
public static doublenextUp(double d)
Returns the floating-point value adjacent to {@code d} in the direction of positive infinity. This method is semantically equivalent to {@code nextAfter(d, Double.POSITIVE_INFINITY)}; however, a {@code nextUp} implementation may run faster than its equivalent {@code nextAfter} call.

Special Cases:

  • If the argument is NaN, the result is NaN.
  • If the argument is positive infinity, the result is positive infinity.
  • If the argument is zero, the result is {@link Double#MIN_VALUE}

param
d starting floating-point value
return
The adjacent floating-point value closer to positive infinity.
since
1.6

	return sun.misc.FpUtils.nextUp(d);
    
public static floatnextUp(float f)
Returns the floating-point value adjacent to {@code f} in the direction of positive infinity. This method is semantically equivalent to {@code nextAfter(f, Float.POSITIVE_INFINITY)}; however, a {@code nextUp} implementation may run faster than its equivalent {@code nextAfter} call.

Special Cases:

  • If the argument is NaN, the result is NaN.
  • If the argument is positive infinity, the result is positive infinity.
  • If the argument is zero, the result is {@link Float#MIN_VALUE}

param
f starting floating-point value
return
The adjacent floating-point value closer to positive infinity.
since
1.6

	return sun.misc.FpUtils.nextUp(f);
    
public static doublepow(double a, double b)
Returns the value of the first argument raised to the power of the second argument. Special cases:
  • If the second argument is positive or negative zero, then the result is 1.0.
  • If the second argument is 1.0, then the result is the same as the first argument.
  • If the second argument is NaN, then the result is NaN.
  • If the first argument is NaN and the second argument is nonzero, then the result is NaN.
  • If
    • the absolute value of the first argument is greater than 1 and the second argument is positive infinity, or
    • the absolute value of the first argument is less than 1 and the second argument is negative infinity,
    then the result is positive infinity.
  • If
    • the absolute value of the first argument is greater than 1 and the second argument is negative infinity, or
    • the absolute value of the first argument is less than 1 and the second argument is positive infinity,
    then the result is positive zero.
  • If the absolute value of the first argument equals 1 and the second argument is infinite, then the result is NaN.
  • If
    • the first argument is positive zero and the second argument is greater than zero, or
    • the first argument is positive infinity and the second argument is less than zero,
    then the result is positive zero.
  • If
    • the first argument is positive zero and the second argument is less than zero, or
    • the first argument is positive infinity and the second argument is greater than zero,
    then the result is positive infinity.
  • If
    • the first argument is negative zero and the second argument is greater than zero but not a finite odd integer, or
    • the first argument is negative infinity and the second argument is less than zero but not a finite odd integer,
    then the result is positive zero.
  • If
    • the first argument is negative zero and the second argument is a positive finite odd integer, or
    • the first argument is negative infinity and the second argument is a negative finite odd integer,
    then the result is negative zero.
  • If
    • the first argument is negative zero and the second argument is less than zero but not a finite odd integer, or
    • the first argument is negative infinity and the second argument is greater than zero but not a finite odd integer,
    then the result is positive infinity.
  • If
    • the first argument is negative zero and the second argument is a negative finite odd integer, or
    • the first argument is negative infinity and the second argument is a positive finite odd integer,
    then the result is negative infinity.
  • If the first argument is finite and less than zero
    • if the second argument is a finite even integer, the result is equal to the result of raising the absolute value of the first argument to the power of the second argument
    • if the second argument is a finite odd integer, the result is equal to the negative of the result of raising the absolute value of the first argument to the power of the second argument
    • if the second argument is finite and not an integer, then the result is NaN.
  • If both arguments are integers, then the result is exactly equal to the mathematical result of raising the first argument to the power of the second argument if that result can in fact be represented exactly as a double value.

(In the foregoing descriptions, a floating-point value is considered to be an integer if and only if it is finite and a fixed point of the method {@link #ceil ceil} or, equivalently, a fixed point of the method {@link #floor floor}. A value is a fixed point of a one-argument method if and only if the result of applying the method to the value is equal to the value.)

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a the base.
param
b the exponent.
return
the value ab.

	return StrictMath.pow(a, b); // default impl. delegates to StrictMath
    
public static doublerandom()
Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0. Returned values are chosen pseudorandomly with (approximately) uniform distribution from that range.

When this method is first called, it creates a single new pseudorandom-number generator, exactly as if by the expression

new java.util.Random
This new pseudorandom-number generator is used thereafter for all calls to this method and is used nowhere else.

This method is properly synchronized to allow correct use by more than one thread. However, if many threads need to generate pseudorandom numbers at a great rate, it may reduce contention for each thread to have its own pseudorandom-number generator.

return
a pseudorandom double greater than or equal to 0.0 and less than 1.0.
see
java.util.Random#nextDouble()

        if (randomNumberGenerator == null) initRNG();
        return randomNumberGenerator.nextDouble();
    
public static doublerint(double a)
Returns the double value that is closest in value to the argument and is equal to a mathematical integer. If two double values that are mathematical integers are equally close, the result is the integer value that is even. Special cases:
  • If the argument value is already equal to a mathematical integer, then the result is the same as the argument.
  • If the argument is NaN or an infinity or positive zero or negative zero, then the result is the same as the argument.

param
a a double value.
return
the closest floating-point value to a that is equal to a mathematical integer.

	return StrictMath.rint(a); // default impl. delegates to StrictMath
    
public static intround(float a)
Returns the closest int to the argument. The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type int. In other words, the result is equal to the value of the expression:

(int)Math.floor(a + 0.5f)

Special cases:

  • If the argument is NaN, the result is 0.
  • If the argument is negative infinity or any value less than or equal to the value of Integer.MIN_VALUE, the result is equal to the value of Integer.MIN_VALUE.
  • If the argument is positive infinity or any value greater than or equal to the value of Integer.MAX_VALUE, the result is equal to the value of Integer.MAX_VALUE.

param
a a floating-point value to be rounded to an integer.
return
the value of the argument rounded to the nearest int value.
see
java.lang.Integer#MAX_VALUE
see
java.lang.Integer#MIN_VALUE

	return (int)floor(a + 0.5f);
    
public static longround(double a)
Returns the closest long to the argument. The result is rounded to an integer by adding 1/2, taking the floor of the result, and casting the result to type long. In other words, the result is equal to the value of the expression:

(long)Math.floor(a + 0.5d)

Special cases:

  • If the argument is NaN, the result is 0.
  • If the argument is negative infinity or any value less than or equal to the value of Long.MIN_VALUE, the result is equal to the value of Long.MIN_VALUE.
  • If the argument is positive infinity or any value greater than or equal to the value of Long.MAX_VALUE, the result is equal to the value of Long.MAX_VALUE.

param
a a floating-point value to be rounded to a long.
return
the value of the argument rounded to the nearest long value.
see
java.lang.Long#MAX_VALUE
see
java.lang.Long#MIN_VALUE

	return (long)floor(a + 0.5d);
    
public static doublescalb(double d, int scaleFactor)
Return {@code d} × 2{@code scaleFactor} rounded as if performed by a single correctly rounded floating-point multiply to a member of the double value set. See the Java Language Specification for a discussion of floating-point value sets. If the exponent of the result is between {@link Double#MIN_EXPONENT} and {@link Double#MAX_EXPONENT}, the answer is calculated exactly. If the exponent of the result would be larger than {@code Double.MAX_EXPONENT}, an infinity is returned. Note that if the result is subnormal, precision may be lost; that is, when {@code scalb(x, n)} is subnormal, {@code scalb(scalb(x, n), -n)} may not equal x. When the result is non-NaN, the result has the same sign as {@code d}.

Special cases:

  • If the first argument is NaN, NaN is returned.
  • If the first argument is infinite, then an infinity of the same sign is returned.
  • If the first argument is zero, then a zero of the same sign is returned.

param
d number to be scaled by a power of two.
param
scaleFactor power of 2 used to scale {@code d}
return
{@code d} × 2{@code scaleFactor}
since
1.6

	return sun.misc.FpUtils.scalb(d, scaleFactor);
    
public static floatscalb(float f, int scaleFactor)
Return {@code f} × 2{@code scaleFactor} rounded as if performed by a single correctly rounded floating-point multiply to a member of the float value set. See the Java Language Specification for a discussion of floating-point value sets. If the exponent of the result is between {@link Float#MIN_EXPONENT} and {@link Float#MAX_EXPONENT}, the answer is calculated exactly. If the exponent of the result would be larger than {@code Float.MAX_EXPONENT}, an infinity is returned. Note that if the result is subnormal, precision may be lost; that is, when {@code scalb(x, n)} is subnormal, {@code scalb(scalb(x, n), -n)} may not equal x. When the result is non-NaN, the result has the same sign as {@code f}.

Special cases:

  • If the first argument is NaN, NaN is returned.
  • If the first argument is infinite, then an infinity of the same sign is returned.
  • If the first argument is zero, then a zero of the same sign is returned.

param
f number to be scaled by a power of two.
param
scaleFactor power of 2 used to scale {@code f}
return
{@code f} × 2{@code scaleFactor}
since
1.6

	return sun.misc.FpUtils.scalb(f, scaleFactor);
    
public static doublesignum(double d)
Returns the signum function of the argument; zero if the argument is zero, 1.0 if the argument is greater than zero, -1.0 if the argument is less than zero.

Special Cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is positive zero or negative zero, then the result is the same as the argument.

param
d the floating-point value whose signum is to be returned
return
the signum function of the argument
author
Joseph D. Darcy
since
1.5

	return sun.misc.FpUtils.signum(d);
    
public static floatsignum(float f)
Returns the signum function of the argument; zero if the argument is zero, 1.0f if the argument is greater than zero, -1.0f if the argument is less than zero.

Special Cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is positive zero or negative zero, then the result is the same as the argument.

param
f the floating-point value whose signum is to be returned
return
the signum function of the argument
author
Joseph D. Darcy
since
1.5

	return sun.misc.FpUtils.signum(f);
    
public static doublesin(double a)
Returns the trigonometric sine of an angle. Special cases:
  • If the argument is NaN or an infinity, then the result is NaN.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a an angle, in radians.
return
the sine of the argument.


                                                                                     
         
	return StrictMath.sin(a); // default impl. delegates to StrictMath
    
public static doublesinh(double x)
Returns the hyperbolic sine of a double value. The hyperbolic sine of x is defined to be (ex - e-x)/2 where e is {@linkplain Math#E Euler's number}.

Special cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is infinite, then the result is an infinity with the same sign as the argument.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 2.5 ulps of the exact result.

param
x The number whose hyperbolic sine is to be returned.
return
The hyperbolic sine of x.
since
1.5

	return StrictMath.sinh(x);
    
public static doublesqrt(double a)
Returns the correctly rounded positive square root of a double value. Special cases:
  • If the argument is NaN or less than zero, then the result is NaN.
  • If the argument is positive infinity, then the result is positive infinity.
  • If the argument is positive zero or negative zero, then the result is the same as the argument.
Otherwise, the result is the double value closest to the true mathematical square root of the argument value.

param
a a value.
return
the positive square root of a. If the argument is NaN or less than zero, the result is NaN.

	return StrictMath.sqrt(a); // default impl. delegates to StrictMath
				   // Note that hardware sqrt instructions
				   // frequently can be directly used by JITs
				   // and should be much faster than doing
				   // Math.sqrt in software.
    
public static doubletan(double a)
Returns the trigonometric tangent of an angle. Special cases:
  • If the argument is NaN or an infinity, then the result is NaN.
  • If the argument is zero, then the result is a zero with the same sign as the argument.

The computed result must be within 1 ulp of the exact result. Results must be semi-monotonic.

param
a an angle, in radians.
return
the tangent of the argument.

	return StrictMath.tan(a); // default impl. delegates to StrictMath
    
public static doubletanh(double x)
Returns the hyperbolic tangent of a double value. The hyperbolic tangent of x is defined to be (ex - e-x)/(ex + e-x), in other words, {@linkplain Math#sinh sinh(x)}/{@linkplain Math#cosh cosh(x)}. Note that the absolute value of the exact tanh is always less than 1.

Special cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is zero, then the result is a zero with the same sign as the argument.
  • If the argument is positive infinity, then the result is +1.0.
  • If the argument is negative infinity, then the result is -1.0.

The computed result must be within 2.5 ulps of the exact result. The result of tanh for any finite input must have an absolute value less than or equal to 1. Note that once the exact result of tanh is within 1/2 of an ulp of the limit value of ±1, correctly signed ±1.0 should be returned.

param
x The number whose hyperbolic tangent is to be returned.
return
The hyperbolic tangent of x.
since
1.5

	return StrictMath.tanh(x);
    
public static doubletoDegrees(double angrad)
Converts an angle measured in radians to an approximately equivalent angle measured in degrees. The conversion from radians to degrees is generally inexact; users should not expect cos(toRadians(90.0)) to exactly equal 0.0.

param
angrad an angle, in radians
return
the measurement of the angle angrad in degrees.
since
1.2

	return angrad * 180.0 / PI;
    
public static doubletoRadians(double angdeg)
Converts an angle measured in degrees to an approximately equivalent angle measured in radians. The conversion from degrees to radians is generally inexact.

param
angdeg an angle, in degrees
return
the measurement of the angle angdeg in radians.
since
1.2

	return angdeg / 180.0 * PI;
    
public static doubleulp(double d)
Returns the size of an ulp of the argument. An ulp of a double value is the positive distance between this floating-point value and the double value next larger in magnitude. Note that for non-NaN x, ulp(-x) == ulp(x).

Special Cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is positive or negative infinity, then the result is positive infinity.
  • If the argument is positive or negative zero, then the result is Double.MIN_VALUE.
  • If the argument is ±Double.MAX_VALUE, then the result is equal to 2971.

param
d the floating-point value whose ulp is to be returned
return
the size of an ulp of the argument
author
Joseph D. Darcy
since
1.5

	return sun.misc.FpUtils.ulp(d);
    
public static floatulp(float f)
Returns the size of an ulp of the argument. An ulp of a float value is the positive distance between this floating-point value and the float value next larger in magnitude. Note that for non-NaN x, ulp(-x) == ulp(x).

Special Cases:

  • If the argument is NaN, then the result is NaN.
  • If the argument is positive or negative infinity, then the result is positive infinity.
  • If the argument is positive or negative zero, then the result is Float.MIN_VALUE.
  • If the argument is ±Float.MAX_VALUE, then the result is equal to 2104.

param
f the floating-point value whose ulp is to be returned
return
the size of an ulp of the argument
author
Joseph D. Darcy
since
1.5

	return sun.misc.FpUtils.ulp(f);