atan

atan

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Calculates the inverse tangent of a number

 #include <math.h> double atan ( double x  ); float atanf ( float x  );         (C99) long double atanl ( long double x  );         (C99) 

atan( ) implements the inverse tangent function, commonly called arc tangent.

The return value is given in radians, and is thus in the range -p/2 atan(x) atanl( 1.0L ); // Because tan(pi/4) = 1 #endif printf( "Assume pi equals %.17Lf.\n", pi);

This code produces the following output:

 Assume pi equals 3.14159265358979324. 

See Also

The arc tangent functions for complex numbers: catan( ), catanf( ), and catanl( )