Calculting a function with limits

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Rasmus
Rasmus 2014-3-1
评论： Rasmus 2014-3-2
Hello guys.
I have a two functions which i need to integrate by using an anonymous function.
but for some reason i says error, first i wanted to use quad, but it seems like it isnt beeing used anymore.
but i think i am misunderstanding something to calculate it.
the two functions are the following:
8/ln(2)*integral(ln(1+tan(x)) lower limit=0 upper limit: pi/4
the next is
integral(2/sqrt(5^2-x^2)) lower limit: 0 upper limit: pi

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回答（2 个）

the cyclist
the cyclist 2014-3-1
I suggest the integral function.
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Rasmus
Rasmus 2014-3-1
I tried using the integral(function,lower limit,upper limit)
does not really want to do as i say, can you tell me how you would make it work?

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Roger Stafford
Roger Stafford 2014-3-2
Your first integral has a singularity at x = 0, but it was my impression that 'integral' can handle such singularities. However, try setting the lower limit just a tiny bit above zero to see if the trouble remains.
Alternatively you can do integration by parts and solve the equivalent:
8/log(2) * ( pi/4*log(2)-integral( @(x) x/cos(x)/(cos(x)+sin(x)) ,0,pi/4) )
which has no singularity.
As for the second integral, it is a perfectly run-of-the-mill integral which 'integral' should have no trouble with. However, you don't really need matlab to evaluate it. By changing variables x = 5*sin(t), it is easy to show that it is exactly equal to 2*asin(pi/5). Why waste effort setting it up for matlab when ordinary calculus procedures are available?
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Rasmus
Rasmus 2014-3-2
I am taking a class in using matlab, so i have to set it up in matlab. I've already calculated it in hand, i just can't make matlab do it as well. The first one i managed now, but the second is still....

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