20.11

java.lang.Math

THE PACKAGE JAVA.LANG

20.11.8

public static double atan(double a)

This method computes an approximation to the arc tangent of the argument, using

the a

tan

 algorithm as published in

fdlibm

 (see the introduction to this section).

Special cases:

If the argument is NaN, then the result is NaN.

If the argument is positive zero, then the result is positive zero; if the argu 

ment is negative zero, then the result is negative zero.

20.11.9

public static double atan2(double y, double x)

This method computes an approximation to the arc tangent of the quotient

y

x

 of

the arguments, using the a

tan2

 algorithm as published in

fdlibm

 (see the intro 

duction to this section).

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

.

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  

.

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 argu 

ment is finite, then the result is the

double

 value closest to

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 argu 

ment is finite, then the result is the

double

 value closest to  

2 .

If both arguments are positive infinity, then the result is the

double

 value

closest to

4 .

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