How to define both integer and decimal increment in one for loop?

Hi all,

I would like to define one for loop that goes from 0 to 1 with an increment of 0.1 and then goes from 1 to 30 by an increment of 2, i.e., combination of the following two loops. Is it possible? If so, how?

for n = 1:2:30
   f(round((n-1)/2+1)) = ....
end
  
  z = 0: 0.1: 1; 
 for n = 1: length(z)
    f(n) = ..
 end

Thanks in advance

Answer 1

[Image Analyst]

Try this:

allValues = [0:0.1:1, 3:2:30];
numValues = length(allValues)
% Preallocate some results we want to store in the loop.
results = zeros(1, numValues);
% Now loop over all values.
for k = 1 : numValues
	thisValue = allValues(k);
	fprintf('Processing element #%d of %d, which is %f.\n', ...
		k, numValues, thisValue);
% 	results(k) = YourFunction(thisValue);
end

[Susan]

Thank you so much, @Image Analyst! Appreciate your help.

Answer 2

[millercommamatt]

I'm not clear on what you're looking for. Do you want something like this:

span1 = 0:0.1:1;
span2 = 3:2:30;
span = [span1 span2];
for ii = span
   % do something with ii...
end

[Susan]

Thanks for your reply.

I want something like what you suggest however I don't know how to deal with the indices in the for loop. Any idea?

span1 = 0:0.1:1;
span2 = 3:2:30;
span = [span1 span2];
for ii = span
   f(?) = something% do something with ii...
end

[millercommamatt]

Do you want to do something like:

span1 = 0:0.1:1;
span2 = 3:2:30;
span = [span1 span2];
output = NaN(length(span),1);
for ii = 1:length(span)
   output(ii) = some_function(span(ii));
end

[Image Analyst]

No. output(ii) will throw an error for fractional ii values.

[millercommamatt]

What are you on about? ii will never be a fractional value.

[Susan]

Thank you so much, @Matthew for your help. Appreciate it!

[Steven Lord]

@Matthew I suspect Image Analyst was replying to Susan's message not yours. The comment "do something with ii..." suggests to me (and I suspect to Image Analyst as well) that Susan wanted output(ii).

[Image Analyst]

I was responding to Susan and just said No, then I went to MATLAB to develop code that works. Then I came back here to further explain why it wouldn't work and edited my comment but then I didn't notice miller's comment since it was posted while I was working on the code in MATLAB, and I mistakenly copied the loop from miller's comment instead of Susan's (not noticing that millers was a new comment). Sorry for the misunderstanding, that sometimes happens when people are posting at the same time. miller's code snippet #2 will also work for Susan.