java.lang
Class Math
java.lang.Object java.lang.Math
public final class Math
- extends Object
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 | |
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static double | E The double value that is closer than any other to e, the base of the natural logarithms. |
static double | PI The double value that is closer than any other to pi, the ratio of the circumference of a circle to its diameter. |
Method Summary | |
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static double | abs(double a) Returns the absolute value of a double value. |
static float | abs(float a) Returns the absolute value of a float value. |
static int | abs(int a) Returns the absolute value of an int value. |
static long | abs(long a) Returns the absolute value of a long value. |
static double | acos(double a) Returns the arc cosine of a value; the returned angle is in the range 0.0 through pi. |
static double | asin(double a) Returns the arc sine of a value; the returned angle is in the range -pi/2 through pi/2. |
static double | atan(double a) Returns the arc tangent of a value; the returned angle is in the range -pi/2 through pi/2. |
static double | atan2(double y, double x) Returns the angle theta from the conversion of rectangular coordinates ( x , y ) to polar coordinates (r, theta). |
static double | cbrt(double a) Returns the cube root of a double value. |
static double | ceil(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 double | copySign(double magnitude, double sign) Returns the first floating-point argument with the sign of the second floating-point argument. |
static float | copySign(float magnitude, float sign) Returns the first floating-point argument with the sign of the second floating-point argument. |
static double | cos(double a) Returns the trigonometric cosine of an angle. |
static double | cosh(double x) Returns the hyperbolic cosine of a double value. |
static double | exp(double a) Returns Euler's number e raised to the power of a double value. |
static double | expm1(double x) Returns ex -1. |
static double | floor(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 int | getExponent(double d) Returns the unbiased exponent used in the representation of a double . |
static int | getExponent(float f) Returns the unbiased exponent used in the representation of a float . |
static double | hypot(double x, double y) Returns sqrt(x2 +y2) without intermediate overflow or underflow. |
static double | IEEEremainder(double f1, double f2) Computes the remainder operation on two arguments as prescribed by the IEEE 754 standard. |
static double | log(double a) Returns the natural logarithm (base e) of a double value. |
static double | log10(double a) Returns the base 10 logarithm of a double value. |
static double | log1p(double x) Returns the natural logarithm of the sum of the argument and 1. |
static double | max(double a, double b) Returns the greater of two double values. |
static float | max(float a, float b) Returns the greater of two float values. |
static int | max(int a, int b) Returns the greater of two int values. |
static long | max(long a, long b) Returns the greater of two long values. |
static double | min(double a, double b) Returns the smaller of two double values. |
static float | min(float a, float b) Returns the smaller of two float values. |
static int | min(int a, int b) Returns the smaller of two int values. |
static long | min(long a, long b) Returns the smaller of two long values. |
static double | nextAfter(double start, double direction) Returns the floating-point number adjacent to the first argument in the direction of the second argument. |
static float | nextAfter(float start, double direction) Returns the floating-point number adjacent to the first argument in the direction of the second argument. |
static double | nextUp(double d) Returns the floating-point value adjacent to d in the direction of positive infinity. |
static float | nextUp(float f) Returns the floating-point value adjacent to f in the direction of positive infinity. |
static double | pow(double a, double b) Returns the value of the first argument raised to the power of the second argument. |
static double | random() Returns a double value with a positive sign, greater than or equal to 0.0 and less than 1.0 . |
static double | rint(double a) Returns the double value that is closest in value to the argument and is equal to a mathematical integer. |
static long | round(double a) Returns the closest long to the argument. |
static int | round(float a) Returns the closest int to the argument. |
static double | scalb(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 float | scalb(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 double | signum(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 float | signum(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 double | sin(double a) Returns the trigonometric sine of an angle. |
static double | sinh(double x) Returns the hyperbolic sine of a double value. |
static double | sqrt(double a) Returns the correctly rounded positive square root of a double value. |
static double | tan(double a) Returns the trigonometric tangent of an angle. |
static double | tanh(double x) Returns the hyperbolic tangent of a double value. |
static double | toDegrees(double angrad) Converts an angle measured in radians to an approximately equivalent angle measured in degrees. |
static double | toRadians(double angdeg) Converts an angle measured in degrees to an approximately equivalent angle measured in radians. |
static double | ulp(double d) Returns the size of an ulp of the argument. |
static float | ulp(float f) Returns the size of an ulp of the argument. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
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