Tuesday, July 9, 2013

java.math.*;

java.lang
Class Math

java.lang.Object
  extended by java.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.


Since:
JDK1.0


Field Summary
static doubleE
          The double value that is closer than any other to e, the base of the natural logarithms.
static doublePI
          The double value that is closer than any other to pi, the ratio of the circumference of a circle to its diameter.

Method Summary
static doubleabs(double a)
          Returns the absolute value of a double value.
static floatabs(float a)
          Returns the absolute value of a float value.
static intabs(int a)
          Returns the absolute value of an int value.
static longabs(long a)
          Returns the absolute value of a long value.
static doubleacos(double a)
          Returns the arc cosine of a value; the returned angle is in the range 0.0 through pi.
static doubleasin(double a)
          Returns the arc sine of a value; the returned angle is in the range -pi/2 through pi/2.
static doubleatan(double a)
          Returns the arc tangent of a value; the returned angle is in the range -pi/2 through pi/2.
static doubleatan2(double y, double x)
          Returns the angle theta from the conversion of rectangular coordinates (xy) to polar coordinates (r, theta).
static doublecbrt(double a)
          Returns the cube root of a double value.
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.
static doublecopySign(double magnitude, double sign)
          Returns the first floating-point argument with the sign of the second floating-point argument.
static floatcopySign(float magnitude, float sign)
          Returns the first floating-point argument with the sign of the second floating-point argument.
static doublecos(double a)
          Returns the trigonometric cosine of an angle.
static doublecosh(double x)
          Returns the hyperbolic cosine of a double value.
static doubleexp(double a)
          Returns Euler's number e raised to the power of a double value.
static doubleexpm1(double x)
          Returns ex -1.
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.
static intgetExponent(double d)
          Returns the unbiased exponent used in the representation of a double.
static intgetExponent(float f)
          Returns the unbiased exponent used in the representation of a float.
static doublehypot(double x, double y)
          Returns sqrt(x2 +y2) without intermediate overflow or underflow.
static doubleIEEEremainder(double f1, double f2)
          Computes the remainder operation on two arguments as prescribed by the IEEE 754 standard.
static doublelog(double a)
          Returns the natural logarithm (base e) of a double value.
static doublelog10(double a)
          Returns the base 10 logarithm of a double value.
static doublelog1p(double x)
          Returns the natural logarithm of the sum of the argument and 1.
static doublemax(double a, double b)
          Returns the greater of two double values.
static floatmax(float a, float b)
          Returns the greater of two float values.
static intmax(int a, int b)
          Returns the greater of two int values.
static longmax(long a, long b)
          Returns the greater of two long values.
static doublemin(double a, double b)
          Returns the smaller of two double values.
static floatmin(float a, float b)
          Returns the smaller of two float values.
static intmin(int a, int b)
          Returns the smaller of two int values.
static longmin(long a, long b)
          Returns the smaller of two long values.
static doublenextAfter(double start, double direction)
          Returns the floating-point number adjacent to the first argument in the direction of the second argument.
static floatnextAfter(float start, double direction)
          Returns the floating-point number adjacent to the first argument in the direction of the second argument.
static doublenextUp(double d)
          Returns the floating-point value adjacent to d in the direction of positive infinity.
static floatnextUp(float f)
          Returns the floating-point value adjacent to f in the direction of positive infinity.
static doublepow(double a, double b)
          Returns the value of the first argument raised to the power of the second argument.
static doublerandom()
          Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0.
static doublerint(double a)
          Returns the double value that is closest in value to the argument and is equal to a mathematical integer.
static longround(double a)
          Returns the closest long to the argument.
static intround(float a)
          Returns the closest int to the argument.
static doublescalb(double d, int scaleFactor)
          Return d × 2scaleFactor rounded as if performed by a single correctly rounded floating-point multiply to a member of the double value set.
static floatscalb(float f, int scaleFactor)
          Return f × 2scaleFactor rounded as if performed by a single correctly rounded floating-point multiply to a member of the float value set.
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.
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.
static doublesin(double a)
          Returns the trigonometric sine of an angle.
static doublesinh(double x)
          Returns the hyperbolic sine of a double value.
static doublesqrt(double a)
          Returns the correctly rounded positive square root of a double value.
static doubletan(double a)
          Returns the trigonometric tangent of an angle.
static doubletanh(double x)
          Returns the hyperbolic tangent of a double value.
static doubletoDegrees(double angrad)
          Converts an angle measured in radians to an approximately equivalent angle measured in degrees.
static doubletoRadians(double angdeg)
          Converts an angle measured in degrees to an approximately equivalent angle measured in radians.
static doubleulp(double d)
          Returns the size of an ulp of the argument.
static floatulp(float f)
          Returns the size of an ulp of the argument.

Methods inherited from class java.lang.Object
cloneequalsfinalizegetClasshashCodenotifynotifyAlltoStringwaitwaitwait

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