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C++ Help Please.......Area under a curve

Discussion in 'C++' started by BobbyK, Mar 3, 2010.

  1. BobbyK

    BobbyK New Member

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    hey all...........

    Im doing an assignment for college and i need help writing a simple program for C++
    its writing a program to calculate the area under a curve and im reallly stuck any help would be brillant. i dont really no how to approach it either. even if u could just copy and paste an actual workable solution to the problem i would be very greatful...........



    cheers...........
     
  2. xpi0t0s

    xpi0t0s Mentor

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    How is the curve defined? If you have an equation for it, e.g. y=x^2+3x+5, then you can calculate the area via the integral [Int(y)=x^3/3+3x^2/2+5x].
     
  3. virxen

    virxen New Member

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  4. BobbyK

    BobbyK New Member

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    for example if it was defined for y=x^2

    I honestly dont have a clue how to write a basic C++ program for it........
    i have to use both rectangles and trapezoids methods to find the area????????????
    :undecided:worried:
     
  5. virxen

    virxen New Member

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    complex trapezoid method for f(x)=x^2 only
    =============================

    Code:
    #include <stdio.h>
    #include <stdlib.h>
    
    double f(float);
    
    int main(){
        float xo,x;
        float a,b,h;
        double integral;
        int n;
        printf("\ngive left x value;:");
        scanf("%f",&a);
        printf("\ngive right x value;:");
        scanf("%f",&b);
        printf("\nenter how many sections you want(bigger more accurate result):");
        scanf("%d",&n);
        //calculations
        h=(b-a)/n;
        integral=(f(a)+f(b))/2;
        for (int i=1;i<n;i++){
            integral+=f(a+i*h);
        }
        integral=integral*h;
        printf("\n the integral of f(x)=x^2,from a=%3f , to b=%3f is %6.3f",a,b,integral);
        getchar();    getchar();
    }
    double f(float x){
    return x*x;
    }
    
     

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