integral

#include <stdio.h>
#include <math.h>
float h,L=0,jum[100],a,b,N,riil=240.917;
int i;
input(){
    printf("Masukkan batas atas (a)\t\t: ");
    scanf("%f",&a);
    printf("Masukkan batas bawah (b)\t: ");
    scanf("%f",&b);
    printf("Masukkan jumlah pembagi (N)\t: ");
    scanf("%f",&N);
}
reimann(){
    printf("================\nIntegral Reimann\n================\n");
    input();

    h = (b-a) / N;
    printf("\nNilai dari H = %0.2f\n",h);

    printf("-------------------------\n");
    printf("   x\t|   f(x)\t|\n");
    printf("-------------------------\n");

    for(i=0;i<=N;i++){
        jum[i]=pow(a,3)+2*pow(a,2);
        L=L+jum[i];
            printf("  %0.2f \t|  %0.2f\t|\n",a,jum[i]);
        a=a+h;
    }
    printf("-------------------------\n");
    L=L*h;
    printf("\nLuasnya adalah %0.3f\n", L);
    printf("Errornya adalah %0.2f\n", L-riil);

}

trapezoida(){
    printf("===================\nIntegral Trapezoida\n===================\n");
    input();

    h = (b-a) / N;
    printf("H = %0.2f\n",h);

    printf("-------------------------\n");
    printf("   x\t|   f(x)\t|\n");
    printf("-------------------------\n");

    for(i=0;i<=N;i++){
        jum[i]=pow(a,3)+2*pow(a,2);
        L=L+jum[i];
            printf("  %0.2f \t|  %0.2f\t|\n",a,jum[i]);
        a=a+h;
    }
    printf("-------------------------\n");
    i--;
    L=h/2*(jum[0]+2*(L-jum[0]-jum[i])+jum[i]);
    printf("\nLuasnya adalah %0.3f\n", L);
    printf("Errornya adalah %0.2f\n", riil-L);
}

title(){
    printf("=========================\n");
    printf("INTEGRAL by Mirra Ariesta\n");
    printf("=========================\n");
}

pilMenu(){
    int pil;
    printf("Pilihan Menu :\n");
    printf("\t1. Integral Reimann\n\t2. Integral Trapezoida\n");
    printf("\nMasukkan Pilihan : ");
    scanf("%d",&pil);
    switch(pil){
    case 1 : system("cls"); reimann();
             break;
    case 2 : system("cls"); trapezoida();
             break;
    default : system("cls"); pilMenu();
             break;
    }
}

char ulangi(){
    char opt;
    fflush(stdin);
    printf("Ulangi [y/t] ? :");
        scanf("%c",&opt);
        if(opt=='y'||opt=='Y')
            opt=1;
        else
            opt=0;
        return opt;
}

int main(){
    title();
    do{
        pilMenu();
    }while(ulangi());
}