Torsten
Posts:
1,714
Registered:
11/8/10


Re: Integration with variable limits
Posted:
Jul 26, 2013 2:41 AM


"Sanaa" wrote in message <kss3h5$50n$1@newscl01ah.mathworks.com>... > "Torsten" wrote in message <ksrcel$2k$1@newscl01ah.mathworks.com>... > > "Sanaa" wrote in message <ksrbia$r0l$1@newscl01ah.mathworks.com>... > > > Hi all, > > > How to integrate a function within a loop and the limits of integration are variables? > > > For instance, y(i)*(1y(i)) is the function I wish to integrate from 0.25*i to t where > > > t \in (0.25*i, 0.25*(i+1)). > > > Any help is really appreciated. > > > Sanaa Moussa > > > > I think y(i)*(1y(i)) is just a real number, not a function, isn't it ? > > > > Best wishes > > Torsten. > > Thanks for replying. You are right, but I mean the function is y*(1y) which I want to put it into a loop > My code is > itermax=300;min=itermax9;% That is we plot from 291:300 i.e. 10 values of x only. > r=0.25; > for rho=0:0.001:4 > %x0=0.1; > x(1)=0.1; > for i=1:itermax1 > %t=linspace(i*r,(i+1)*r,itermax) > y(i+1)=x(i); > x(i+1)=x(i)+ rho*int(y(i)*(1y(i)),i*r,(i+1)*r); > end > %fix(y) > plot(rho*ones(10),x(min:itermax),'b.','linewidth',0.1) > hold on > end > fsize=15; > xlabel('\rho','FontSize',fsize) > ylabel('\itx','FontSize',fsize) > %title('r=0.25, \alpha=1','FontSize',fsize) > hold off > % print(gcf, 'djpeg', 'zbuffer', 'bif.png'); > > I get the error > Function 'int' is not defined for values of class 'double'. > what does this mean and how to fix it please? > Many thanks in advance.
It means what I said before: y(i)*(1y(i)) is a scalar value and not a function. So "int" does not know how to handle this because it expects a function, not a scalar as its first input argument.
Best wishes Torsten.

