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- NAME
- #include <libraries/mathffp.h>
#include <aros/libcall.h>
#include <proto/mathffp.h>
#include <proto/mathtrans.h>
#include <proto/exec.h>
#include <exec/types.h>
float SPCos ()
- SYNOPSIS
- float fnum1
- FUNCTION
- Calculate the cosine of a given ffp number in radians
- INPUTS
- fnum1
- Motorola fast floating point number
- RESULT
- Motorola fast floating point number
flags:
zero : result is zero
negative : result is negative
overflow : 0
- NOTES
-
- EXAMPLE
- BUGS
-
- SEE ALSO
- MathTrans
- INTERNALS
- Algorithm for Calculation of cos(y):
z = floor ( |y| / pi );
y_1 = |y| - z * pi; => 0 <= y_1 < pi
if (y_1 > pi/2 ) then y_1 = pi - y_1;
=> 0 <= y_1 < pi/2
Res = 1 - y^2/2! + y^4/4! - y^6/6! + y^8/8! - y^10/10! =
= 1 -(y^2(-1/2!+y^2(1/4!+y^2(-1/6!+y^2(1/8!-1/10!y^2)))));
if (z was an odd number)
Res = -Res;
if (y_1 was greater than pi/2 in the test above)
Res = -Res;
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