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MathSupport.javaAPI DocphoneME MR2 API (J2ME)12362Wed May 02 18:00:34 BST 2007com.sun.perseus.platform

# MathSupport

public final class MathSupport extends Object
 This class is used to provide URL resolution.
 version\$Id: MathSupport.java,v 1.5 2006/04/21 06:34:50 st125089 Exp \$

Fields Summary
public static final float
PI
The `double` value that is closer than any other to pi, the ratio of the circumference of a circle to its diameter.
Constructors Summary
Methods Summary
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.

 parama the argument whose absolute value is to be determinedreturnthe absolute value of the argument.seejava.lang.Integer#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))`

 parama the argument whose absolute value is to be determinedreturnthe absolute value of the argument.

``````        return (a <= 0.0F) ? 0.0F - a : a;
``````
public static floatatan(float a)
Returns the arc tangent of an angle, in the range of -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.

A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

 parama the value whose arc tangent is to be returned.returnthe arc tangent of the argument.

``````	//atan(x) = x/(1+ 0.28*x^2) (|x|<=1)
//atan(x) = pi/2 - x/(x^2 + 0.28) (|x| >=1)

if (MathSupport.abs(a) <= 1.0f) {
return (a /(1 + 0.28f*(a*a)));
} else {
float retval = (((float)Math.PI)/2.0f) - (a/((a*a) + 0.28f));
if (a < (-1.0f)){
return (retval - (float)Math.PI);
} else {
//if a > 1.0f
return retval;
}
}
``````
public static floatatan2(float y, float x)
Converts rectangular coordinates (`x``y`) to polar (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 `float` 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 `float` 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 `float` 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 `float` value closest to -pi/2.
• If both arguments are positive infinity, then the result is the `float` value closest to pi/4.
• If the first argument is positive infinity and the second argument is negative infinity, then the result is the `float` 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 `float` value closest to -pi/4.
• If both arguments are negative infinity, then the result is the `float` value closest to -3*pi/4.

A result must be within 2 ulps of the correctly rounded result. Results must be semi-monotonic.

 paramy the ordinate coordinateparamx the abscissa coordinatereturnthe theta component of the point (r, theta) in polar coordinates that corresponds to the point (x, y) in Cartesian coordinates.

``````	// if x=y=0
if((y == 0.0f) && (x == 0.0f)) {
return 0.0f;
}

// if x>0 atan(y/x)
if(x > 0.0f) {
return atan(y/x);
}

// if x<0 sign(y)*(pi - atan(|y/x|))
if(x < 0.0f) {
if(y < 0.0f) {
return (float)(-(Math.PI - MathSupport.atan(y/x)));
} else {
return (float)(Math.PI - MathSupport.atan(-y/x));
}
}

// if x=0 y!=0 sign(y)*pi/2
if(y<0.0f) {
return (float)(-(Math.PI/2.0f));
} else {
return (float)(Math.PI/2.0f);
}

``````
public static floatcos(float a)
Returns the trigonometric cosine of an angle. Special cases:
• If the argument is NaN or an infinity, then the result is NaN.

A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

 parama an angle, in radians.returnthe cosine of the argument.

``````

return (float) Math.cos(a);
``````
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`.

 parama a floating-point value to be rounded to an integer.returnthe value of the argument rounded to the nearest `int` value.seejava.lang.Integer#MAX_VALUEseejava.lang.Integer#MIN_VALUE

``````        return (int) Math.floor(a + 0.5f);
``````
public static floatsin(float 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.

A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

 parama an angle, in radians.returnthe sine of the argument.

``````        return (float) Math.sin(a);
``````
public static floatsqrt(float a)
Returns the correctly rounded positive square root of a `float` 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 `float` value closest to the true mathematical square root of the argument value.

 parama a value. returnthe positive square root of `a`. If the argument is NaN or less than zero, the result is NaN.

``````        return (float) Math.sqrt(a);
``````
public static floattan(float 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.

A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

 parama an angle, in radians.returnthe tangent of the argument.

``````        return (float) Math.tan(a);
``````
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`.
 paramangrad an angle, in radiansreturnthe measurement of the angle `angrad` in degrees.since1.2
``````        return angrad * 180.0f / PI;
 paramangdeg an angle, in degreesreturnthe measurement of the angle `angdeg` in radians.since1.2
``````        return angdeg / 180.0f * PI;