Java中Math方法举例

Question

Java中Math方法举例

Answer 1

sin
public static double sin(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.
A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Parameters:
a - an angle, in radians.
Returns:
the sine of the argument.

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cos
public static double cos(double 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.

Parameters:
a - an angle, in radians.
Returns:
the cosine of the argument.

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tan
public static double tan(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.
A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Parameters:
a - an angle, in radians.
Returns:
the tangent of the argument.

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asin
public static double asin(double a)Returns the arc sine of an angle, in the range of -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.
A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Parameters:
a - the value whose arc sine is to be returned.
Returns:
the arc sine of the argument.

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acos
public static double acos(double a)Returns the arc cosine of an angle, in the range of 0.0 through pi. Special case:
If the argument is NaN or its absolute value is greater than 1, then the result is NaN.
A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Parameters:
a - the value whose arc cosine is to be returned.
Returns:
the arc cosine of the argument.

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atan
public static double atan(double 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.

Parameters:
a - the value whose arc tangent is to be returned.
Returns:
the arc tangent of the argument.

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toRadians
public static double toRadians(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.

Parameters:
angdeg - an angle, in degrees
Returns:
the measurement of the angle angdeg in radians.
Since:
1.2

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toDegrees
public static double toDegrees(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.

Parameters:
angrad - an angle, in radians
Returns:
the measurement of the angle angrad in degrees.
Since:
1.2

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exp
public static double exp(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.
A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Parameters:
a - the exponent to raise e to.
Returns:
the value ea, where e is the base of the natural logarithms.

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log
public static double log(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.
A result must be within 1 ulp of the correctly rounded result. Results must be semi-monotonic.

Parameters:
a - a number greater than 0.0.
Returns:
the value ln a, the natural logarithm of a.

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sqrt
public static double sqrt(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.

Parameters:
a - a value.
Returns:
the positive square root of a. If the argument is NaN or less than zero, the result is NaN.

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IEEEremainder
public static double IEEEremainder(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.

Parameters:
f1 - the dividend.
f2 - the divisor.
Returns:
the remainder when f1 is divided by f2.

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ceil
public static double ceil(double a)Returns the smallest (closest to negative infinity) double value that is not less than 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).

Parameters:
a - a value.
Returns:
the smallest (closest to negative infinity) floating-point value that is not less than the argument and is equal to a mathematical integer.

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floor
public static double floor(double a)Returns the largest (closest to positive infinity) double value that is not greater than 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.

Parameters:
a - a value.
Returns:
the largest (closest to positive infinity) floating-point value that is not greater than the argument and is equal to a mathematical integer.

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rint
public static double rint(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.

Parameters:
a - a double value.
Returns:
the closest floating-point value to a that is equal to a mathematical integer.

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atan2
public static double atan2(double y,
double 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 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.
A result must be within 2 ulps of the correctly rounded result. Results must be semi-monotonic.

Parameters:
y - the ordinate coordinate
x - the abscissa coordinate
Returns:
the theta component of the point (r, theta) in polar coordinates that corresponds to the point (x, y) in Cartesian coordinates.

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pow
public static double pow(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 ceil or, equivalently, a fixed point of the method 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.)

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

Parameters:
a - the base.
b - the exponent.
Returns:
the value ab.

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round
public static int round(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.

Parameters:
a - a floating-point value to be rounded to an integer.
Returns:
the value of the argument rounded to the nearest int value.
See Also:
Integer.MAX_VALUE, Integer.MIN_VALUE