Numerical integration in matlab2018

Dear Friends,

This looks simple but am not able to get it. Could you help me out.

I have the following variable in a equation that needs to be integrated

its like

L = linspace(0.3,4.5,2000);

T = 100;

fun = @(T) ((0.4175./L.^3) - (0.6643./L.^2) + (0.9036./L) + 3.5332 - 0.0744.*L).*10^-5.*(1 + 0.00276.*T);

q = integral(fun,20,T)

However, when i rum this, iam getting an error. Could you help me out on solving this.

[Adam Danz]

The integral() function evaluates your function between x=20 and x=100 (your inputs) and expects to receive a single value as an output for each input. It then computes the integral under that curve.

Your function is returning a vector of outputs 2000 elements long for each input.

[Pavan Kumar]

I dint get you completely...

Do i need to use a for loop for this kind of integration?

[Adam Danz]

Check out these examples provided by matlab (link below). When you evalue the functions in those example, you'll see that they return a single value.

https://www.mathworks.com/help/matlab/ref/integral.html#btbbkta-5

When I evaluate your function, a vector is returned:

>> fun(20)
ans =
  Columns 1 through 6
   0.00015411   0.00015159   0.00014914   0.00014676   0.00014444    0.0001422
  Columns 7 through 12
   0.00014002    0.0001379   0.00013584   0.00013383   0.00013189   0.00012999
  Columns 13 through 18
   0 ...... (2000 elements long)

Did you expect that your function returns a single value or do you expect that it returns a vector?