加速这个Matlab代码？

Question

Is there a good way to speed up this block of matlab code ( n in particular, can be large) using matrix operations, or anything? Over 1/4 of my execution time is in this small block of code.

% Get the bin indexes that we will place the network in
bins = [];
for n=low_freq:0.5:high_freq;
    bins = [bins, (n-spec_start)/spec_bin_size+1];
end

Test code:

spec_start=2400
spec_bin_size=0.5
low_freq = 2437
high_freq=2438

bins = [];
for n=low_freq:0.5:high_freq;
    bins = [bins, (n-spec_start)/spec_bin_size+1];
end

bins  % 75 76 77

bins = [];
bins = (low_freq:0.5:high_freq - spec_start)./spec_bin_size + 1;

bins  % empty?

Answer 1

You can skip the loop:

bins = ((low_freq:0.5:high_freq) - spec_start)./spec_bin_size + 1;

In situations where you can't do vectorized calculations as above, you should at least preallocate the output array