How to use my TRIG Library

Since GNU treats inline functions slightly differently to CW the 1st thing to 
note is that if you are using GNU change the line in trig.h that reads
//#define GNU_C
to
#define GNU_C

the makefile is for the GNU C trigtest program
the trig.mcp file is for the CW trigtest program

The angles are defined as positive integers 0-4095 clockwise from due north 
0   degrees = 0 PSX units
90  degrees = 1024 PSX units
180 degrees = 2048 PSX units
270 degrees = 3096 PSX units (same as -90 degrees)
360 degrees = 4096 PSX units

The function values are in 12bit fixed point. so
1.0  = 4096 (this is #defined in libps.h as ONE)
0.5  = 2048
etc.


Function Descriptions

Conversion
int Deg2PSX(int DegAngle)       - converts from angle in degrees to angle in PSX. Returns angle in PSX units
int PSX2Deg(int PSXAngle)	- converts from angle in PSX units to angle in degrees. Returns angle in degrees

PSX unit functions
int TanP(int PSXAngle)		- returns Tan of PSX angle. Return Value is 12 bit fixed point
int SinP(int PSXAngle)		- returns Sin of PSX angle. Return Value is 12 bit fixed point
int CosP(int PSXAngle)		- returns Cos of PSX angle. Return Value is 12 bit fixed point
int ATanP(int X)                - returns Atan of X (X is in 12 bit fixed point, angle returned in PSX units)
int ASinP(int X)                - returns Asin of X (X is in 12 bit fixed point, angle returned in PSX units)
int ACosP(int X)                - returns Acos of X (X is in 12 bit fixed point, angle returned in PSX units)

Degree functions
int TanD(int DegAngle)		- returns Tan of angle. Return Value is 12 bit fixed point
int SinD(int DegAngle)		- returns Sin of angle. Return Value is 12 bit fixed point
int CosD(int DegAngle)		- returns Cos of angle. Return Value is 12 bit fixed point
int ATanD(int X)                - returns Atan of X (X is in 12 bit fixed point, angle returned in degrees)
int ASinD(int X)                - returns Asin of X (X is in 12 bit fixed point, angle returned in degrees)
int ACosD(int X)                - returns Acos of X (X is in 12 bit fixed point, angle returned in degrees)

Misc
u_long ISqrt(u_long X)		- returns integer square root of X
TrigTest(void)                  - tests all of the above functions

Usage

   | dx /
   |   /
dy |  /
   |A/
   |/

to find the angle A of the above triangle

val=(dx*4096)/dy;	// alternatively for better readability val=(dx*ONE)/dy
A=ATanP(val);		// A is angle in PSX units
A=ATanD(val);		// A is angle in degrees

Similarly knowing the angle A and length dy find dx

A in degrees

val=TanD(A);
dx=(val*dy)/ONE;

A in PSX units

val=TanP(A);
dx=(val*dy)/ONE;



Any questions feedback appreciated


Nick Slaven
NickSlaven@compuserve.com