Is there any way to use a for-loop in MATLAB with a custom step? What I want to do is iterate over all powers of 2 lesser than a given number. The equivalent loop in C++ (for example) would be:
for (int i = 1; i < 65; i *= 2)
Note 1: This is the kind of iteration that best fits for-loops, so I'd like to not use while-loops.
Note 2: I'm actually using Octave, not MATLAB.
Perhaps you want something along the lines of
for i=2.^[1:6]
disp(i)
end
Except you will need to figure out the range of exponents. This uses the fact that since
a_(i+1) = a_i*2 this can be rewritten as a_i = 2^i.
Otherwise you could do something like the following
i=1;
while i<65
i=i*2;
disp(i);
end
You can iterate over any vector, so you can use vector operations to create your vector of values before you start your loop. A loop over the first 100 square numbers, for example, could be written like so:
values_to_iterate = [1:100].^2;
for i = values_to_iterate
i
end
Or you could loop over each position in the vector values_to_iterate (this gives the same result, but has the benefit that i keeps track of how many iterations you have done - this is useful if you are writing a result from each loop sequentially to an output vector):
values_to_iterate = [1:100].^2;
for i = 1:length(values_to_iterate)
values_to_iterate(i)
results_vector(i) = some_function( values_to_iterate(i) );
end
More concisely, you can write the first example as simply:
for i = [1:100].^2
i
end
Unlike in C, there doesn't have to be a 'rule' to get from one value to the next. The vector iterated over can be completely arbitrary:
for i = [10, -1000, 23.3, 5, inf]
i
end