Problem solving integral?

2012 5 22
1 个回答
7 次查看（30 天）

0 个投票

Hi all,
I want to calculate the integral of my function f(x) but I get the error of Explicit integral could not be found. My codes are:
syms x
B=0.5;
C=2;
D=1.2;
S=1;
f=2.^(-log2(1/B)*(((S-x)./C).^D));
int(f,x)
can anybody help me please with it?
Thank you in advance Sasi

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回答（1 个）

Walter Roberson
Walter Roberson 2012-5-22

0 个投票

There is no closed form expression for that integral that I have been able to find. You will need to use numeric integration.
Note: using floating point powers in an integral is always a problem. Does 1.2 mean 6/5 or 12/10 or something else? The results are different depending on which representation of the power that you choose. If you use a floating point representation then the results are defined in terms of complex logs that will give complex numbers for negative arguments even in cases where we would normally find a negative real root. For example, (-8)^0.333333 is a complex number, whereas (-8)^(1/3) could be -2

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Sasi
Sasi
2012-5-22

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