Take values from array within nested loop

Want to implement

RMSE= sqrt{1/K* summation k=1:K [(theta_est-theta_true)]^2}
theta_est and theta_true may be of different length

error=0;
for k=1:K
  for m=1:length(theta_est)
    for t=1:length(theta_true)
      error=error+(theta_est(m,k)-theta_true(t,k)).^2
      RMSE=sqrt(1/K*error)
    end
  end
end

[David Sanchez]

And what is your problem?

Answer 1

[dpb]

"Implement RMSE= sqrt{1/K* summation k=1:K [(theta_est-theta_true)]^2} [where] theta_est and theta_true may be of different length"

Well, there's no definition of a difference where there aren't comparable entities so your choice is either compute over the min(length(theta_est),length(theta_true)) or, if the two vectors represent a given time of commensurate duration, interpolate the shorter or decimate the longer to match. The first option is simply

K=min(length(theta_est),length(theta_true));
RMSE=rms(theta_est(1:K)-theta_true(1:K));      % rms from Signal Processing Toolbox