I am working on a problem involving Taylor's Series of cosine x and sine x. (cosx = 1 - (x^2/2!) + (x^4/4!) - ...)

My only problem is how I can do the alternating plus minus on each term. This is the code I currently have in which I can't still figure out if it is right or wrong.

double cosine(double x)

{

int n, ctr;

double cos;

cos = 0;

n = 2*NUMBER_OF_TERMS;

ctr = NUMBER_OF_TERMS;

while(ctr > 0)

{

ctr--;

cos = cos + (RaiseTo(x, n)/factorial(n));

cos *= -1;

n -= 2;

}

return cos;

}

*Note: We were only allowed to use stdio.h as the header file.