INT will not evalaute integral
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I have a code that needs to evalaute the arc length equation below:
syms x
a = 10;
b = 10;
c = 10;
d = 10;
fun = 4*a*x^3+3*b*x^2+2*c*x+d
int((1+(fun)^2)^.5)
but all that returns is below:
ans =
int(((40*x^3 + 30*x^2 + 20*x + 10)^2 + 1)^(1/2), x)
Why wont matlab evaluate this integral? I added a line under to check if it would evaulate int(x) and it returned the desired result.
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Answers (1)
Mischa Kim
on 30 Jun 2014
Edited: Mischa Kim
on 30 Jun 2014
Dan, try instead
int((1+fun^2)^5,x)
or
vpa(int((1+fun^2)^5,x),4)
for better readability.
2 Comments
Mischa Kim
on 30 Jun 2014
Well, there is probably no closed-form solution, which is why MATLAB's Symbolic Math Toolbox won't do the trick. In this case, use numeric integration.
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