c - The function ceil() is ignored -

i have question regarding ceil() function. following code try round 2 decimal places in c variable monthlypayment, , ceil function seems ignored in output. in image output compared supposed be. img

#include "stdafx.h" #include "stdio.h" #include "math.h" #define months 12  int main() {     double principle;     double rate;     double numyears;     double nummonths;     double monthlypayment;     double monthlyrate;      printf("welcome morgage calculator.\nenter principal amount started. ");     scanf_s("%lf", &principle);     printf("enter yearly morgage interest rate ");     scanf_s("%lf", &rate);     printf("enter number of years ");     scanf_s("%lf", &numyears);     nummonths = numyears * months;     monthlyrate = rate / months / 100;     monthlypayment = ((monthlyrate) / (1 - pow((1 + monthlyrate), (-nummonths)))* principle);     monthlypayment = monthlypayment * 100;     ceil(monthlypayment);     monthlypayment = monthlypayment / 100;     double toprince = 0.0;     double interest = 0.0;     printf("your total monthly payment ammount:$ %.2lf\n", monthlypayment);     printf("month\tprinciple\tinterest\t $ principle\n");         (int index = 1; index <= nummonths;) {             interest = principle * monthlyrate;             toprince = monthlypayment - interest;                printf("%2d%16.2lf %16.2lf %16.2lf\n", index, principle, interest, toprince);             principle = principle - toprince;             index++;         } } 

ceil() not alter variable provided returns result. should be:

double result = ceil(var);