Not having Integration result

I am trying to integrate this function using the code -

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syms x

xd = 700/319

fun = ((x^4)* exp(x))/((exp(x) -1)^2);

cv = int(fun,0,xd)

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But, I am getting same form of the function like that -

>> Cv_calculatior

cv =

int((x^4*exp(x))/(exp(x) - 1)^2, x, 0, 700/319)

What's wrong here??

Answer 1

[Torsten]

Using "int", MATLAB tries to find an analytical antiderivative for your function, but cannot find one.

Use numerical integraion using "integral" instead. Don't start at 0 since your function has a division by zero at this location.

fun = @(x) x.^4.*exp(x)./(exp(x) -1).^2;
xd = 700/319;
result = integral(fun,1e-16,xd)

[Mohammad Humaun Kabir]

Thanks. Would you like to help me to write the whole code. Here is my problem -

Varying temparature from 0 degree to 800 degree with 2 degree interval ( T = 0:2:800)

integrating this function, y = ((x.^4).* exp(x))./((exp(x) -1).^2) for 0 to T, where T has a range of data

Expecting result: a list of data, T vs y

[Torsten]

fun = @(x) x.^4.*exp(x)./(exp(x) -1).^2;
T = [1e-16,2:2:800];
y(1) = 0;
for i = 2:numel(T)
  y(i) = y(i-1) + integral(fun,T(i-1),T(i));
end
plot(T,y)