### _fcossin -- Calculate Cosine and Sine

Format

>     #include <builtin.h>
>     double _fcossin(double x, double *y);

Language Level: Extension
_fcossin calculates the cosine of x, and stores the sine of x in *y. This is faster than separately calculating the sine and cosine. Use _fcossin instead of _fsincos when you will be using the cosine first, and then the sine. This function causes the compiler to emit the FSINCOS 80387 instruction.

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

- You cannot take the address of _fcossin.
- You cannot parenthesize a _fcossin function call, because parentheses specify a call to the backing code for the function in the library.

Return Value
_fcossin returns the cosine of x.

Example
This example calculates the cosine of x and stores it in z, and stores the sine of x in *y.

    #include <builtin.h>
    #include <stdio.h>

    int main(void)
    {
       double x, y, z;

       printf("Enter x:\n");
       scanf("%lf", &x);

       z = _fcossin(x, &y);
       printf("The cosine of %lf is %lf.\n", x, z);
       printf("The sine of %lf is %lf.\n", x, y);
       return 0;

       /**********************************************
          Assuming you enter: 1.0

          The output should be:

          The cosine of 1.000000 is 0.540302.
          The sine of 1.000000 is 0.841471.
       **********************************************/
    }

acos -- Calculate Arccosine
asin -- Calculate Arcsine
cos -- Calculate Cosine
cosh -- Calculate Hyperbolic Cosine
_facos -- Calculate Arccosine
_fasin -- Calculate Arcsine
_fcos -- Calculate Cosine
sin -- Calculate Sine
sinh -- Calculate Hyperbolic Sine
_fsin -- Calculate Sine
_fsincos -- Calculate Sine and Cosine
<builtin.h>