matlab interp C code generation, Waring: comparing floating point with == or != is unsafe
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I use interp1,interp2 in a .m file and generate C code, then the _sharedutils folder has a new xxxxx_interp1.c file to realize interp function, but the generated C code use "if floating point == floating point ", so C complier warn: comparing floating point with == or != is unsafe, how can I solve the problem in matlab and let it generate the rigtht C code.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1042520/image.png)
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Answers (2)
SlipperyGnome
on 23 Jun 2022
When comparing floating point numbers, because of very small rounding off errors, using '==' or '!=' will generate compiler warnings.
You can set an error tolerance upto the magnitude you need it to be same.
num1=0.8-0.5;
num2=0.3;
Error_tolerance= (1e-15)*max(num1,num2);
if (abs(num1-num2) < Error_tolerance)
disp(0);
else
disp("not 0")
end
This tolerance value method would work accurately upto 1e-15. You can also go to this link for better understanding.
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SlipperyGnome
on 1 Jul 2022
One of the ways is you can try remodelling with a lookup table block, which can henceforth generate better code for you.
Hope this helps!
Szabolcs Fodor
on 25 Oct 2023
Hello there,
did you found a reasonable solution for this issue? I'm facing similar issues and this is a big no for our embeded system.
Please get back to me if you found a solution.
Cheers,
Szabi
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