# How to read just the powers from matlab output

2 views (last 30 days)
Ole on 18 Jun 2020
Commented: Image Analyst on 19 Jun 2020
How to read/print the powers from the matlab output function coeffs ?
l^4*w^3*z^1 and l^4*w^3
I would like to obtain numbers 341 and 340 from the above sequence.
[r, t] = coeffs(10*z^2*w^4 + 5*w^2*l^2 + 2*z^6)
t =
[ l^2*w^2, w^4*z^2, z^6]
% 220 402 006

Ameer Hamza on 19 Jun 2020
How are the terms separated? If separated using '+' operator, then try the following code
str = '10*z^2*w^4 + 5*w^2*l^2 + 2*z^6';
patterns = {'w\^([0-9]*)', 'l\^([0-9]*)', 'z\^([0-9]*)'};
tokens = cellfun(@(p) {regexp(strsplit(str, '+'), p, 'tokens')}, patterns);
y = cellfun(@(token) {cellfun(@helperFun, token)}, tokens);
y = reshape(cell2mat(y(:)), 1, []);
function y = helperFun(x)
if ~isempty(x)
y = str2double(x{1}{1});
else
y = 0;
end
end
Result
>> y
y =
4 0 2 2 2 0 0 0 6
Image Analyst on 19 Jun 2020
Oh, that could be another interpretation. I was wondering how he got those numbers. Let's hope for clarification from Ole. It seems he has totally forgotten about this question he posted.

Image Analyst on 18 Jun 2020
Here's one way, using isstrprop():
chr = 'l^4*w^3*z^1 and 8^4*w^3' % Create test character array.
mask = isstrprop(chr,'digit') % Get locations of numbers
caretLocations = chr == '^'
caretLocations = [false, caretLocations(1:end-1)] % Shift to the right.
numbers = sscanf(chr, ' %f')
Image Analyst on 19 Jun 2020
Results:
numbers =
4
3
1
4
3