## Find the limits of integration for a known area ! HELP!

### AstroandreaNASA (view profile)

on 30 Apr 2013

Hey. Any help would be really appreciated .

I'm trying to make a program but i don't even know how to start.

This is the problem:

I already have a script that computes this integral with b given.

integral (e^((-x)^2))/sqrt(pi) dx from x=0 to b *

Now I need to make one which uses the fact of a known area under the curve so i can compute b !

A

## Products

No products are associated with this question.

### the cyclist (view profile)

on 30 Apr 2013

Here is an example where instead of your function, I did a simpler one (the area under the line y = x). You should be able to just swap in your function for F.

```% This function calculates the area under the curve for the function f(x) = x
F = @(x) 0.5*x.^2;
```
```% Suppose the desired area is 4.5 The function G will be zero when the area
% under the curve is 4.5
G = @(x)(F(x) - 4.5);
```
```% This will find the critical value of x (which you have called "b") for which
% G is zero, which gives the area under the curve you want.
b = fzero(G,1)
```