Legacy Document

Inside Macintosh: Operating System Utilities /

Chapter 3 - Mathematical and Logical Utilities / Mathematical and Logical Utilities Reference

Routines / Performing Calculations on Fixed-Point Numbers

FracCos

You can use the FracCos function to obtain a fast approximation of the cosine of a Fixed number.

FUNCTION FracCos (x: Fixed): Fract;

x

The Fixed number expressed in radians, whose cosine is to be calculated.

DESCRIPTION

The FracCos function returns the cosine, expressed in radians, of the Fixed number x.

The approximation of Pi/4 used to compute the cosine is the hexadecimal value 0.C910, making the approximation of Pi equal to 3.1416015625, while Pi itself equals 3.14159265.... Despite the approximation of Pi, the cosine value obtained is usually correct to several decimal places.