Date:	26 MAR 97 09:38:46 DST
From:	DBerry1 AT dca DOT gov DOT au
Subject:	Newbie troubles with Sin and Cos
To:	djgpp AT delorie DOT com
MIME-Version:	1.0
Message-ID:	<0000oqkoqioy.0000nzhphlnh@dca.gov.au>

G'day

I've just started playing around with DJGPP and have come across the 
following problem.

I'm trying to write a routine that spins a pixel around in a circle.  That 
works ok so far, except that the X and Y points are never next to each 
other - I think I have narrowed it down to the results I am getting from 
using COS and SIN.

for instance here's the output from a simple prog I did to test my idea

Sin of 0 is 0.000000
Sin of 1 is 0.841471
Sin of 2 is 0.909297
Sin of 3 is 0.141120
Sin of 4 is -0.756802

But using a calculator I get

Sin of 0 is 0
Sin of 1 is 0.017452
Sin of 2 is 0.034899
Sin of 3 is 0.052335
Sin of 4 is 0.069756

Here's the simple prog...

#include <math.h>
#include <stdlib.h>
#include <stdio.h>

float result = 0.0;
int theta = 0;

main ()
{
while (theta < 360)
{
result = sin(theta);
printf ("Sin of %i is %f\n",theta,result);
theta++;
}
return 0;
}

Am I using the wrong variable types to hold the results ?  Do I need to do 
something special in DJGPP to get the magic numbers ?

Thanks
dberry AT dca DOT gov DOT au

- Raw text -