Searching for help on matlab : Warning: Explicit integral could not be found
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Hello,
I'm trying to solve definite integral on MATLAB, but there is always an Error Message: Warning: Explicit integral could not be found.
The function include syms x y
f= -exp(-(249*(x + (15*y)/83 - 105/83)^2)/(25*(y/250 - 7/250)))/(y - 7)
>> int(f,y,0,7) but the following message occurs Warning: Explicit integral could not be found.
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Answers (2)
Walter Roberson
on 26 Dec 2013
Not every integral has a closed algebraic form. You are probably going to have to use numeric integration.
What kind of value are you expecting for "x" ? Your integral gets into large values very very quickly. The division by (y-7) is not going to do you any numeric favors as y goes to 7.
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Roger Stafford
on 27 Dec 2013
Edited: Roger Stafford
on 27 Dec 2013
As it stands, this integral is divergent at its upper limit of integration. It's no wonder the warning was issued. The argument of 'exp' is always positive as y approaches 7 from below, so the value of exp(...) is always greater than or equal to one. The indefinite integral of 1/(y-7) would be log(7-y) which becomes minus infinity as y approaches 7, so the same holds true of this integral.
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