c++ programming help pls? why isn't my for loop working? and why do i get zero at

Y

Your Majesty

New member
the end? include <stdio.h>
#include <math.h>
main () {
int n,g;
double a,b,tmp,f,x,delta,sum;

printf("Enter the extremes of the interval [a,b]: ");
scanf("%lf %lf", &a, &b);


if (b>a)
printf("'a'=%lf 'b'=%lf\n", a ,b);

else if (a>b){
printf("a>b, swapping a and b\n");
tmp=a;a=b;b=tmp;
}


printf("Enter the number of points (n):");
scanf("%d", &n);

if (n>0)
{
if (n%2==0)
printf("'n'=%d\n", n);

else if (n%2!=0)
{
printf("'n' must be an even number. setting 'n=n++'\n");
printf("old 'n'=%d\n",n++);
printf("new'n'=%d\n",n);
}
}
else if (n<=100)
{
printf("'n' must be positive. Setting 'n =100'\n");
n=100;
printf("'n'=%d\n", n);
}



printf("Integrating \n f(x) =0.5sin^2(x)+0.25 on [%f,%f]"
"using %d points\n", a ,b,n);

/*
delta=(b-a)/n;
x=a;
f=0.5*sin(x)*sin(x) + 0.24;
sum=f;
x=b;
f=0.5*sin(x)*sin(x) + 0.24;
sum +=f;
sum/=2;
for(x=a+delta; x<(b-delta/2); x+=delta)
sum +=0.5*sin(x)*sin(x) +0.25;
sum *=delta;
printf("integral =%f\n", sum);
*/

delta=(1/n)*(b-a);
x=a;
f=0.5*sin(x)*sin(x) + 0.25;
sum=f;
x=b;
f=0.5*sin(x)*sin(x) + 0.24;
sum +=f;

printf("%f\n",sum);

for (x=a+delta; x<((b-delta)/2);x+=delta+delta)
sum +=4.*(0.5*sin(x)*sin(x) +0.25);
printf("%f\n",sum);

for (x=a+delta+delta; x<(((b-delta)/2)-1);x+=delta+delta)
sum +=2.*(0.5*sin(x-1)*sin(x-1) +0.25);
printf("%f\n",sum);
sum*=delta*(1/3.);
printf("integral =%f\n", sum);
"hw5.c" 113 lines, 2249 characters
iacs5.ucsd.edu% gcc hw5.c -lm
iacs5.ucsd.edu% a.out
Enter the extremes of the interval [a,b]: 1 2
'a'=1.000000 'b'=2.000000
Enter the number of points (n):4
'n'=4
Integrating
f(x) =0.5sin^2(x)+0.25 on [1.000000,2.000000]using 4 points
1.257448
1.257448
1.257448
integral =0.000000

thank you very much in advance > <
 
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