## Why is my MATLAB plot wrong?

### Edward Lisa (view profile)

on 18 May 2018
Latest activity Edited by KALYAN ACHARJYA

### KALYAN ACHARJYA (view profile)

on 21 May 2018
Hi! I just started my Matlab course and i have run into a little problem which i hope you can help me with. I am suppose to write a function which integrates a function e^(-t^2) from 0 to some x which is a variable in the function. I did that like this:
function y = simpson_method(x)
y1 = exp(-0.^2);
y2 = exp(-(x).^2);
c = 0;
d = 0;
incr = 0.1;
for i = 1 : (x - 0)/incr - 0.5
y = exp(-(0 + i*incr).^2);
if i/2 == floor(i/2)
d = d + y;
continue
else
c = c + y;
continue
end
end
y = incr/3 * (y1 + 4*c + 2*d + y2);
The function integrates correctly and gives me a desired output for every x. But the problem is when i try to plot it:
x = 0:0.1:15;
y = simpson_method(x);
plot(x,y)
It gives me the wrong graph which i find weird because all the outputs are correct. I get this which is nonsense. Whats happening?
%

Stephen Cobeldick

### Stephen Cobeldick (view profile)

on 18 May 2018
@Edward Lisa: can you please confirm the ambiguous syntax:
1. e^((-t)^2)
2. e^(-(t^2))
Edward Lisa

### Edward Lisa (view profile)

on 18 May 2018
Its e^(-(t^2))

on 21 May 2018
If your y values are correct I can see no reason at all why plot would not give the correct answer so your y values cannot be correct if you are literally just calling plot.

R2017b

### KALYAN ACHARJYA (view profile)

on 21 May 2018
Edited by KALYAN ACHARJYA

### KALYAN ACHARJYA (view profile)

on 21 May 2018

Shown Graph the x ranges are different