Matlab: func2str from a function in a m-file - matlab

Question

In a main m-file I have
conformal = maketform('custom', 2, 2, [], #conformalInverse_0001, []);
used in imtransform that refers to the function defined in conformalInverse_0001.m:
function U = conformalInverse_0001(X, ~)
%#codegen
U = [zeros(size(X))];
Z = complex(X(:,1),X(:,2));
W = 1./(4.*Z.^2-1);
U(:,2) = imag(W);
U(:,1) = real(W);
How can I get the string '1./(4.*Z.^2-1)' in the main program?

Answer 1

I found a way to solve it, but it's not so elegant...
Assume conformalInverse_0001.m is a file in your folder.
You can parse the file as a text file, and search for your formula.
Example:
Assume you know the location is 5'th line in file, and start with W =.
You can use something like the following code to read '1./(4.*Z.^2-1)' in the main program:
%Open file for reading.
fid = fopen('conformalInverse_0001.m', 'r');
%Read 5 lines.
s = textscan(fid, '%s', 5, 'delimiter', '\n');
fclose(fid);
%Get the 5'th line.
s = s{1}(5);
%Convert cell array to string.
s = s{1};
%Get characters from the 5'th character to one char before end of string.
s = s(5:end-1)
Result: s = 1./(4.*Z.^2-1)
You can check textscan documentation for finding more elegant solution.

Answer 2

I'm not sure I fully understand the problem here, but what about adding into your conformalInverse_0001 function something like:
str = '1./(4.*Z.^2-1)';
save('temp_str','str') % or whatever data that you want to save from it
and then adding in your main file:
load('str.mat')% or you can use 'impordata'
where you want to extract it.

Answer 3

I have hacked two solutions with textscan: first knowing the line number and second searching the line that starts with substring 'W = '
% read line line_num = 5 and process string
f_id = fopen(conformalInverse_m_path);
conformalInverse_cell = textscan(f_id,'%s','delimiter','\n'); %disp(conformalInverse_cell); % {68×1 cell}
func_string = conformalInverse_cell{1}{line_num}; disp(func_string); % W = 1./(4.*Z.^2-1); OK
func_string_2=func_string(5:end-1); disp(func_string_2); % 1./(4.*Z.^2-1); OK
% read first line that starts with substring 'W = ' and process string
W_string = 'W = ';
for i=1:100
func_string = conformalInverse_cell{1}{i};
Firt4=func_string(1:4); %disp(['i = ', num2str(i), ': First4 = ', Firt4]);
if strcmp(Firt4,W_string) == 1; line_nr = i; break; end;
end
func_string_2 = conformalInverse_cell{1}{line_nr};
func_string_3=func_string_2(5:end-1);