How to access and modify values of variables in matlab workspace?

Question

There are few variables in my matlab workspace, lets say a and b. eg: a = 1:5; b = 1:10;

I used who to get their names.

like listVariables = who;

now listVariables has the variable names a and b, but i dont know how to access their values so that I can do some mathematical operations on them.

I wouldnt recommend to do this at all, however, check the eval function of matlab (eval(listVariables(1).name)) — Irreducible
– Irreducible, Commented Jan 21, 2020 at 9:26
May I ask what the use-case is? I mean, why would you do mathematical operations on variables you do not know? — Nicky Mattsson
– Nicky Mattsson, Commented Jan 21, 2020 at 10:18
@NickyMattsson, I am using matlab filter design tool and it has an option to import the coefficients designed in the tool to the workspace. on these coefficients i want to do some fixed point conversion,scaling etc — srk_cb
– srk_cb, Commented Jan 21, 2020 at 11:09
Arent the variables names predefined, meaning they always will be the same? — Irreducible
– Irreducible, Commented Jan 21, 2020 at 12:32
The names can be changed during export. Maybe saving to mat and loading a strict is an option. — Daniel
– Daniel, Commented Jan 21, 2020 at 18:38

Rotem · Accepted Answer · 2020-01-21 17:44:12Z

1

It looks like evalin is what your are searching for:

a_val = evalin('base', listVariables{1});
b_val = evalin('base', listVariables{2});

The advantage of evalin is that it can be executed from a function (out of the scope of the workspace).

Example:

In workspace:

a = 1:5; b = 1:10;

Content of my_fun.m:

function my_fun()

listVariables = evalin('base', 'who');

a_val = evalin('base', listVariables{1});
b_val = evalin('base', listVariables{2});

display(a_val);
display(b_val);

Result of my_fun() execution:

a_val =

     1     2     3     4     5


b_val =

     1     2     3     4     5     6     7     8     9    10

Note: there are cases in which evalin is useful, but it's not a good coding practice.

answered Jan 21, 2020 at 17:44

Rotem

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1 Comment

srk_cb Over a year ago

exactly what i was looking for, Thank you

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