[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: how to solve this error mesages from this program?

From: Colin Macdonald
Subject: Re: how to solve this error mesages from this program?
Date: Fri, 8 Feb 2019 12:05:18 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

On 2019-02-07 7:23 a.m., Doug Stewart wrote:
  There seems to be a problem with the eval() function when it is used with
the results from a symbolic calculation.
  The function given above calculates a symbolic matrix which it is
then trying to convert it to a numeric answer. I tried to use double instead of eval but it still did not work. I then tried subs() to convert each symbolic symbol to a number and that also failed. In the end I had to convert it to a function_handle
and then evaluate it at the given values.

Thanks!   I have filed:

It would be great if someone can test the attached script in a somewhat recent version of Matlab (with the Symbolic Toolbox) and report the results, either via email or directly to the bug report.

Should the eval function work for this case?

I'm not sure. I can't find documentation for @sym/eval from the Mathworks, perhaps its somewhat deprecated? My theory is it should do the same as `double(subs(f))`.

`subs(f)` is known not to work (and the error message should make this clear). But if people are using these things, then `subs(f)` seems semantically better than `eval(f)` so I've filed

These sorts of non-explicit commands are pretty magical (dig around in your workspace, find value of variables; I'm not a fan).


Attachment: symevaltest.m
Description: Text Data

reply via email to

[Prev in Thread] Current Thread [Next in Thread]