Function with for loop doesn't always work

Question

Daniel 2024-4-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2109701-function-with-for-loop-doesn-t-always-work

评论： Voss 2024-4-22

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!

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Dyuman Joshi 2024-4-21

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

Is the spacing inconsistent?

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Answer 1

VBBV 2024-4-21

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2109701-function-with-for-loop-doesn-t-always-work#answer_1445146

在 MATLAB Online 中打开

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'.

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VBBV 2024-4-22

编辑：VBBV 2024-4-22

在 MATLAB Online 中打开

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 