## ATAN2 intrinsic function

### Standard: F77 F90 F95 F2003 F2008 Example program

### ＜Syntax＞

ATAN2 ( Y, X )

X : Real;

Y : Same type and kind as X, conformable with X;
the NAG Fortran Compiler also permits Y to have a different kind (this is non-standard);

Result : Same type as X, with kind the same as the kind of X+Y.

### ＜Semantics＞

The value of the result is an approximation to the arc tangent of Y/X, where Y is the sine and X is the cosine. The result is in radians, in the range −π≤ATAN2(Y,X)≤π.

Like many intrinsic functions, this is **elemental**; if either (or both) of X and Y is an array, the result will be an array with that shape, with the value being computed elementwise.

### ＜Related＞

ATAN intrinsic function, ATANH intrinsic function, COS intrinsic function, SIN intrinsic function, TAN intrinsic function