Matlab Interprets Simple MuPad Code Differently than MuPad
5 views (last 30 days)
Show older comments
When the Mupad code below is saved in a MuPad program file, it produces very different results depending on whether it is being run from a MuPad notebook or from the Matlab command window.
x:=0:
if x~=0 then
Result:="Program is being run from MuPad":
else
Result:="Program is being run from Matlab":
end_if:
return(Result)
Basically, MuPad is interpreting ~= as the _approx function and Matlab is interpreting it as meaning "not equal." This caused code that had been working fine in Matlab 2010a to produce incorrect results when run from Matlab 2012b.
Currently, I am just calling the _approx function directly instead of using ~=, but it seems that MuPad code should be interpreted the same way whether it is being run from a MuPad notebook or from a Matlab script. Is this a bug, or is it the intended behavior?
2 Comments
Walter Roberson
on 12 Oct 2012
How are you triggering running the file from the MATLAB command window ?
Answers (1)
Wendy Fullam
on 16 Oct 2012
From development: The behavior is as designed and not a bug.
The Symbolic Math Toolbox (MATLAB side) uses a special definition of ~= which overrides MuPAD’s ~= . This means that MuPAD’s ~= no longer means “approximately equal”, but “unequal” like in MATLAB.
An easier example to see this is
evalin(symengine,'bool(1~=0)')
which returns TRUE in MATLAB since 1 is not equal to 0, but FALSE in MuPAD since they are not approximately equal.
2 Comments
Walter Roberson
on 16 Oct 2012
I agree. And we need to know what else might have a "special definition".
See Also
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!