_fpatan -- Calculate Arctangent

Format

#include <builtin.h>
double _fpatan(double x);

Language Level: Extension
_fpatan calculates the arctangent of x, which is a value in radians between -PI/2 and PI/2. This function causes the compiler to emit the appropriate 80387 instruction for the calculation of arctangent.

Because it is a built-in function and has no backing code in the library:

Return Value
This function returns the arctangent of x.

Example
This example calculates the arctangent of x.

#include <builtin.h>
#include <stdio.h>
int main(void)
{
   double x;
   x = 0.45;
   printf("The arctangent of %lf is %lf.\n", x, _fpatan(x));
   return 0;
   /********************************************************
      The output should be :
      The arctangent of 0.450000 is 0.422854.
   ********************************************************/
}



atan - atan2 -- Calculate Arctangent
_fptan -- Calculate Tangent
tan -- Calculate Tangent
tanh -- Calculate Hyperbolic Tangent
<builtin.h>