Subscripted assignment dimension mismatch

Hello! I have the following problem: Matlab tells me there is a "subscripted assignment dimension mismatch". This the code I'm trying to run:

    N = 1:20;  
    extrapolatedmaturities = 1:100;
    Price = zeros(s,length(extrapolatedmaturities));
    for t = 1:s
        for i = 1:length(extrapolatedmaturities)
            Price(t,:) = exp(-UFR*i)+...
              (z(:,t)'*SWfunction(N,maturities2,alpha,UFR));
        end
    end

Where UFR is a number, z is a N by t matrix (which I invert) and SWfunction produces a N by N matrix. What I want matlab to do is to produce a t by i matrix where for all columns it computes exp(-UFR*i) and up to N add it to the second term, in which it should take for each t the row of values in z, multiply it by the NxN matrix from the SWfunction. Can someone help me? I've tried so many ways of doing this and it always tells me there is a dimension mismatch...

Answer 1

[Thorsten]

The term exp(-UFR*i) is indepent of t, so you could compute it as

 for i = 1:length(extrapolatedmaturities)
   expUFR(i) = exp(-UFR*i);
 end

And then use

 for t = 1:s
   Price(t,:) = expUFR + z(:,t)'*SWfunction(N,maturities2,alpha,UFR);
 end

[Catarina]

Thank you!

[Guillaume]

Actually, for even speedier calculation, you can calculate expUFR without a loop:

expUFR = exp(-UFR*(1:length(extrapolatedmaturaties)));

or even

expUFR = exp(-UFR*extrapolatedmaturaties); %since extraxxx is 1:100

[Guillaume]

And also, unless SWfunction output can change for the same input that can also be calculated once out of the loop, since it doesn't depend on t either:

expUFR = exp(-UFR*extrapolatedmaturaties)
SWvalue = SWfunction(N, maturities2, alpha, UFR);
for t = 1:s
   Price(t, :) = expUFR + z(:, t)' * SWvalue;
end

And I'm sure even the t loop could be vectorised although I can't think how right now.