Function with for loop doesn't always work

I've written a function that writes a C structure into a header file using fprintf(). It seems to not work at all when the input array is small and works partially when the input array is big.

function deg = path2header(fid, deg, comment, option)
% Print path into a header file
% The angle can be set as 'rad', 'deg', or 'rev' in the option.
%   fid      - File indentity
%   deg      - [deg, vmax, amax, dwell]
%   comment  - Name of the path
%   option   - 'rad', 'deg', or 'rev'

if strcmp(option,'rad')
    deg = deg./(2*pi);
elseif strcmp(option,'deg')
    deg = deg./360;
elseif strcmp(option,'rev')

else
    disp("Error option in path2header()")
    return
end

[nseg,m]=size(deg);
disp(nseg)
fprintf(fid,'//---%s\n', comment);
fprintf(fid,'//---%s\n', datestr(now,0));

fprintf(fid,'    char        headerTime[] = "%s";\n',datestr(now,0));
fprintf(fid,'    int         nseg = %d;              // number of points\n',nseg);
fprintf(fid,'    seg\tmySegs[%d]={   // define the array of points in revs\n',nseg);
for i = 1:nseg-1
    fprintf(fid,'        {');
    for j = [1,2,3]
        fprintf(fid,'%e, ',deg(i,j));
    end
    fprintf(fid,'%e},\n',deg(i,4));
end
fprintf(fid,'        {');
for j = [1,2,3]
    fprintf(fid,'%e, ',deg(nseg,j));
end
fprintf(fid,'%e},\n',deg(nseg,4));

fprintf(fid,'}\n        };\n');

This is an example of the test code that results in an empty testPath.h file.

clear;
deg = [ones(3,3), zeros(3,1)];

HeaderFileName = "testPath.h";
fid = fopen(HeaderFileName,'W');
comment = "matlab sramp";
path2header(fid, deg, comment, 'rev')

The function is part of a bigger script to convert angles from an inverse kinematics equation to be saved as C header file to preprogram a motor's path thus the n x 4 matrix.

Please help. Thx!

[Dyuman Joshi]

How does it "not work"? Please specify in the context of your question.

Is the spacing inconsistent?

Answer 1

[VBBV]

With option as rev, it wont work, since the variable deg is undefined

option = 'rev' % with   this option it wont 

option = 'rev'

if strcmp(option,'rad')
    deg = deg./(2*pi);
elseif strcmp(option,'deg')
    deg = deg./360;
elseif strcmp(option,'rev')
else
    disp("Error option in path2header()")
    return
end
[nseg,m]=size(deg)

Unrecognized function or variable 'deg'.

[VBBV]

option = 'rev' % with   this option it wont 

option = 'rev'

deg = [ones(3,3), zeros(3,1)];
if strcmp(option,'rad')
    deg = deg./(2*pi);
elseif strcmp(option,'deg')
    deg = deg./360;
elseif strcmp(option,'rev')
    deg = deg;  % add this line 
else
    disp("Error option in path2header()")
    return
end
[nseg,m]=size(deg)

nseg = 3

m = 4

[VBBV]

If the function is part of bigger script, maybe the fid has changed as result of operations, you can close the open file after every call to function as

lear;
deg = [ones(3,3), zeros(3,1)];
HeaderFileName = "testPath.h";
fid = fopen(HeaderFileName,'W');
comment = "matlab sramp";
if fid == -1
    disp('error message')
else
    path2header(fid, deg, comment, 'rev')   
    fclose(fid)  %  add this line 
end 

[Voss]

deg = deg;

is not necessary.

If option is 'rev', then deg will be as passed in to the function - no need to assign it to itself.

Answer 2

[Voss]

fclose the file, and you'll see it's not empty.

[Daniel]

Ah yes, that's the fix. I should've noticed this if I wasn't writing the script late at night while extremely tired. Thank you!

[Voss]

You're welcome!