CODEWITHSUNDEEP
matlabmupad
tam
tam

Reputation: 141

Error using mupadmex, Error in sym/symsum (Evaluate a definite integral)

I am trying to evaluate a definite integral using the following code :

m=4;
t=4;
n=5;
P=10;
reset(symengine)
syms x;
syms k;

mean=int(log(1+P*x/t)*symsum( factorial(k)*x^(n-m)*exp(-x)/factorial(k+n-m)*feval(symengine,'laguerreL',n-m,k,x)*feval(symengine,'laguerreL',n-m,k,x),k,[0,m-1]) ,x,0,inf)

But it gives the following error: 

  Error using mupadmex
  Error in MuPAD command: The number of arguments is incorrect. [has]
  Evaluating: sum

  Error in sym/symsum (line 114)
  rSym = mupadmex('symobj::map',fsym.s,'symobj::symsum',x.s,a.s,b.s);

  Error in Untitled2 (line 32)
  mean=int(log(1+P*x/t)*symsum( factorial(k)*x^(n-m)*exp(-x)/factorial(k+n-m)*feval(symengine,'laguerreL',n-m,k,x)*feval(symengine,'laguerreL',n-m,k,x),k,[0,m-1]) ,x,0,inf)

However, when I evaluate the integral without some functions:

mean=int(log(1+P*x/t)*symsum( feval(symengine,'laguerreL',n-m,k,x)*feval(symengine,'laguerreL',n-m,k,x),k,[0,m-1]) ,x,0,inf)

I get an answer which is Inf. Any idea?

Upvotes: 0

Views: 927

Answers (1)

tam
tam

Reputation: 141

I found the solution. it consists in using gamma(k+n-m+1) to compute (k+n-m)!, since there is a bug when performing the factorial of a symbolic variables.

Upvotes: 2

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