function kernelCosf( x ) {
	var r;
	var w;
	var z;

	z = x * x;
	w = z * z;
	r = polyval23( z );
	return f32( ( ( 1.0 + ( z*C0 ) ) + ( w*C1 ) ) + ( ( w*z ) * r ) );
}
Computes the cosine of a number on \\( \[-\pi/4, \pi/4] \\) in single-precision floating-point format, where \\( \pi/4 \approx 0.785398164 \\).

## Notes

-   \\( | \cos(x) - c(x) | < 2^{-34.1} \\), where \\( 2^{-34.1} \approx \[ -5.37 \times 10^{-11}, 5.295 \times 10^{-11} \] \\).

@param {number} x - input value (in radians, assumed to be bounded by ~pi/4 in magnitude)
@returns {number} cosine

@example
var v = kernelCosf( 0.0 );
// returns ~1.0

@example
var v = kernelCosf( 3.141592653589793/6.0 );
// returns ~0.866

@example
var v = kernelCosf( 0.785 );
// returns ~0.707

@example
var v = kernelCosf( NaN );
// returns NaN