Symbolic Toolbox: "error using replace"

In version 2025b:

syms a b c x
f = a*x^2+b*x+c

f = 

gives error message:

Error using replace

Too many input arguments

This used to work fine (at least up to version 2023a, I also noted the issue in version 2024b).

Any idea what's going wrong anyone?

[Paul]

Works fine here in 2025b Update 1. Can you copy/paste the entire error message (all of the red text) as in edit to your question or in a repsonse to this comment?

matlabRelease

ans = 
  matlabRelease with properties:

    Release: "R2025b"
      Stage: "release"
     Update: 1
       Date: 05-Sep-2025

syms a b c x
f = a*x^2+b*x+c

f = 

[Henri]

Thanks Paul. Here is the entire error message:

Error using replace

Too many input arguments.

Error in

sym/disp (line 59)

allstrs = replace(allstrs, char(1), "

"); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Error in sym/display>displayVariable (line 97) disp(value,novars) ^^^^^^^^^^^^^^^^^^ Error in sym/display (line 58) displayVariable(namestr,X,symSuggestions,true); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[Sam Chak]

@Henri, I'm not sure what you did, but I attempted to create a situation that leads to the error.

syms a b c x
f = a*x^2+b*x+c

f = 

str1 = char(f);
str2 = "x";
str3 = "y";

% normal
f = replace(str1, str2, str3)

f = 'c + b*y + a*y^2'

% abnormal
f = replace(str1, str2, str3, 1)

Error using replace
Too many input arguments.

[Stephen23]

At first glance it looks like the wrong REPLACE is being called by the symbolic display routine.

Please show the complete output of this command:

which replace -all 

/MATLAB/toolbox/matlab/strfun/replace.m
replace is a built-in method                                                                               % string method
replace is a Java method                                                                                   % java.lang.String method
/MATLAB/toolbox/matlab/testframework/unittest/core/+matlab/+unittest/+plugins/+plugindata/ResultDetails.m  % matlab.unittest.plugins.plugindata.ResultDetails method
replace is a Java method                                                                                   % java.util.HashMap method
replace is a Java method                                                                                   % java.util.AbstractMap method
replace is a Java method                                                                                   % java.util.Map method
replace is a Java method                                                                                   % java.util.Collections$UnmodifiableMap method
/MATLAB/toolbox/matlab/bigdata/@tall/replace.m                                                             % tall method
/MATLAB/toolbox/mbc/mbclayouts/@xregcontainer/replace.m                                                    % xregcontainer method
/MATLAB/toolbox/mbc/mbcview/@cgddnode/replace.m                                                            % cgddnode method
/MATLAB/toolbox/parallel/array/distributed/@codistributed/replace.m                                        % codistributed method

[Henri]

C:\Program Files\MATLAB\R2025b\toolbox\matlab\strfun\replace.m % Shadowed

replace is a built-in method % string method

C:\Program Files\MATLAB\R2025b\toolbox\matlab\bigdata\@tall\replace.m % tall method

C:\Program Files\MATLAB\R2025b\toolbox\mbc\mbclayouts\@xregcontainer\replace.m % xregcontainer method

C:\Program Files\MATLAB\R2025b\toolbox\mbc\mbcview\@cgddnode\replace.m % cgddnode method

C:\Program Files\MATLAB\R2025b\toolbox\parallel\array\distributed\@codistributed\replace.m % codistributed method

[Torsten]

@Henri

Does it work if you use "replace" outside the symbolic environment ?

What do you get from the critical command

z = replace('fsdds''fsfd',char(1),"")

z = 'fsdds'fsfd'

?

[Henri]

Error using replace

Too many input arguments.

[Torsten]

I'm confused.

The usual MATLAB "replace" function seems to be shadowed by another function "replace" with the same name, but this shadowing function is not listed in your output from

which replace -all

Do you know of a function with name "replace.m" that you've created and that is saved somewhere on your MATLAB path ?

[Walter Roberson]

@Henri

What shows up if you command

dbtype 'C:\Program Files\MATLAB\R2025b\toolbox\matlab\strfun\replace.m' 1:3

Also, try

which replace('ab','a','c')

Answer 1

[Henri]

@Torsten Hopp indeed, another replace.m in my Matlab path, that's embarrassing having warned students about this kind of thing for the last 35 years... So, all sorted. Thank you all for your contributions!