CODEWITHSUNDEEP
cseries
comp32
comp32

Reputation: 241

e^-x MacLaurin Series Expansion

I am trying to compute the MacLaurin series for e-x = 1 - x + (x2 / 2!) - (x3 / 3!) +...

My values seem to work up to a certain point and then deviate completely. Is there something wrong with rounding or am I using the wrong type of variable for such a question?

int i;
double sum=0;
double x = 8.3;

for(i=0; i<26; i++)
{
    sum = sum+ (((pow(-1,i)) * (pow(x,i)))/factorial(i));
    printf("Sum = %.12f\n\n\n",sum);
}

return 0;

I don't understand why, but up to the 12th term, the values are correct but after that, it begins to completely differ.

Upvotes: 0

Views: 1675

Answers (1)

R.. GitHub STOP HELPING ICE
R.. GitHub STOP HELPING ICE

Reputation: 215627

Presumably your factorial function, which you're not showing, is performing integer arithmetic. After 12! you're going to overflow a 32-bit integer. Switch to using double in the factorial function too.

Upvotes: 1

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