Using a string as a command?

Let's say I have x=linspace(0,10), and y='x.^2', as a string. How do I tell MatLab to apply y to x? What I am asking is, in the command window, I can type yy=x.^2 to get the desired result. But, I am writing a script and I need to be able to take the string 'x.^2' and tell MatLab yy=x.^2, so I get a yy double that I can plot in the linspace I created. However, simply typing yy=y just creates another string yy='x.^2'.

Answer 1

[Jing]

You can do that by using 'eval'. When y is the string, try the following command.

yy=eval(y);

[Walter Roberson]

This is not recommended.

[Jing]

Why not?

Answer 2

[Andrei Bobrov]

eg:

str = 'x.^2';
yy = str2func(['@(',char(symvar(str)),')',str]);

use

x = 0:10;
out = yy(x);

ADD

str = 'x^2 - y^2'

k = strcat(symvar(str),',');
k = [k{:}];
yy = str2func(['@(',k(1:end-1),')',vectorize(str)]);

use

x = 1:10;
y = linspace(5,20,10);

out = yy(x,y);

[Andrei Bobrov]

added

Answer 3

[Walter Roberson]

f = str2func( ['@(x) ' TheString] );
yy = f(x);