How do I change the format of symbolic output

When I type:

>> syms x y

>> solve(y-x^2,x)

I get:

ans =

[ 1/2 ]

[y ]

[ ]

[ 1/2]

[-y ]

How do I change the output format so to get MATLAB code (with * and ^), which by the way is what I used to get (before today)?

[VBBV]

@Peter van der Kamp use texlabel function

syms x y
sol = solve(y-x^2,x);
sol

sol = 

solStr = texlabel(sol)

solStr = '[-{y}^{{1}/{2}}; {y}^{{1}/{2}}]'

[Peter van der Kamp]

Thanks, it's nice to know that I can turn things into tex. But it's not what I want. I'd like to define the solutions as branches of a multivalued function which I can feed back into MATLAB. Of course, this is just a simple example which I created for the issue I'm having. I used to get my answer in the following format: e.g. sqrt(5/2 + sqrt(w^2 + 9/4)) which is what I'm after. I'm using version R2022b.

Answer 1

[Dyuman Joshi]

Change the symbolic preference of Type-setting as follows -

syms x y

sol = solve(y-x^2,x)

sol = 

%Preference changed (Default value is true)
sympref('TypesetOutput',false);
%Check the output now
sol

 
sol =
 
-y^(1/2)
 y^(1/2)
 

[Peter van der Kamp]

MATLAB returns me the following error:

Unrecognized function or variable 'sympref'.

[Dyuman Joshi]

Do you have the Symbolic Math Toolbox licensed and installed?

Also, which version of MATLAB are you using?

[Peter van der Kamp]

I'm using MATLAB R2022b, all was working fine untill today. Something has definitely changed! It has not complained about license issues. Can you tell me how to check that the Symbolic Toolbox is still licensed and installed? Thanks for your help

[Dyuman Joshi]

Enter the command "ver" in the command window and see if it is installed.

However, if you can run the code you have shown, you should have it installed.

Run these commands

restoredefaultpath;
rehash toolboxcache

and after that check (and share) the output of this particular command -

which sympref -all

/MATLAB/toolbox/symbolic/symbolic/sympref.m

[Peter van der Kamp]

Typing ver gave me a big list, which did not contain "Symbolic Math Toolbox". I'll spare you the list, but have it on file for the IT-department. Then I typed what you said and it gave me:

C:\Program Files\MATLAB\R2022b\toolbox\symbolic\symbolic\sympref.m

Then I typed ver again and I got, somewhere in the list:

Symbolic Math Toolbox Version 9.2 (R2022b)

Hurray!

However, when I now type syms x y I get:

The class 'sym' is used in its own class definition as a base class, property value, or attribute

value. This is not allowed.

Error in syms (line 231)

defined = sym(zeros(1, length(args)));

[Peter van der Kamp]

When closing MATLAB and reopening I'm back to where I was, namely

syms x y

>> solve(x-y^2,y)

ans =

[ 1/2 ]

[x ]

[ ]

[ 1/2]

[-x ]

and ver giving me a list which does not include the Symbolic Math Toolbox. Current plan is to ask IT to reinstall MATLAB and hope this solves the problem. Thanks again!

[Dyuman Joshi]

Based on your comments, things seem to be mixed up.

Yes, reinstalling MATLAB should clear the issue.

Let us know what happens after reinstalling.

[Peter van der Kamp]

Hi Dyuman, good news here:

>> syms x y

>> solve(x-y^2,y)

ans =

-x^(1/2)

x^(1/2)

After reinstalling MATLAB and restarting my computer, things are working well again. IT suggested that maybe a restart of the computer could have fixed the problem (I tend to not do that often enough, sorry).

Cheers,

Peter

Answer 2

[Ninad]

Hi Peter,

If you're using MATLAB version R2016b or newer, you can use "string(sol)" to convert the solution to a string format.

For versions older than R2016b, please use "char(sol)" to achieve the same outcome.

Below is a code snippet for your reference:

>> syms x y

>> sol = solve(y-x^2,x);

>> solStr = string(sol);

>> solChar = string(sol);

>> disp(solStr)
    "-y^(1/2)"
    "y^(1/2)"

>> disp(solChar)
    "-y^(1/2)"
    "y^(1/2)"

I hope you find this information helpful.

Regards,

Ninad

[Peter van der Kamp]

I'm on R2022b, when I type string(sol) I get:

Error using string

Conversion to string from sym is not possible.