>> I have been trying to use cosine and sine in my application.
>> I have tried to use math.h but this doesn't seem to be a palmfile.
>> Does anyone have a suggestion?
Here's some code that's worked fine for me. Hope it helps.
Regards,
Steve Mann
# # #
#define MINUS_ONE ( double ) -1.0
#define DEGS360_RADIANS 360.0 * DEGREES_TO_RADS
#define MAX_COS_ITERATIONS 10
#define MAX_SIN_ITERATIONS 10
/*****************************************************
__sin
Calculate the sin of a double radians angle.
Approximation is x - ( x**3 / 3! ) + ( x**5 / 5! ) - ( x**7 / 7! ) + ...
*****************************************************/
double __sin ( double x ) {
double result, numerator, denominator, term, sign, factorial, x1;
int cnt = 0;
// scale input angle to proper range of values
x1 = x;
while ( x1 > DEGS360_RADIANS ) {
x1 = x1 - DEGS360_RADIANS;
}
// initialize everything
result = x1;
numerator = x1;
denominator = ONE;
factorial = ONE;
sign = MINUS_ONE;
for ( cnt = 0; cnt < MAX_SIN_ITERATIONS; cnt++ ) {
// calculate the next term
numerator = numerator * x1 * x1;
denominator = denominator * ( factorial + ONE ) * (
factorial + TWO );
term = numerator / denominator;
result = result + ( sign * term ) ;
// prepare for next sequence thru loop
sign = sign * MINUS_ONE;
factorial = factorial + TWO;
}
return result;
}
/*****************************************************
__cos
Calculate the cos of a double radians angle
Approximation is 1 - ( x**2 / 2! ) + ( x**4 / 4! ) - ( x**6 / 6! ) + .....
*****************************************************/
double __cos ( double x ) {
double result, numerator, denominator, term, sign, factorial, x1;
int cnt = 0;
// scale input angle to proper range of values
x1 = x;
while ( x1 > DEGS360_RADIANS ) {
x1 = x1 - DEGS360_RADIANS;
}
// initialize everything
result = ONE;
numerator = x1 * x1;
denominator = TWO;
factorial = TWO;
sign = MINUS_ONE;
for ( cnt = 0; cnt < MAX_COS_ITERATIONS; cnt++ ) {
// calculate the next term
term = numerator / denominator;
result = result + ( sign * term ) ;
// prepare for next sequence thru loop
numerator = numerator * x1 * x1;
denominator= denominator * ( factorial + ONE ) * (
factorial + TWO );
factorial = factorial + TWO;
sign = -sign;
}
return result;
}
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