How to get a function from user without knowing its symbols
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Hi everyone I want to create a general program which users insert their desired function and my program do a mathematic operation (like integration) on it and gives the answer. The problem is that i don't know what is the function and its variable, it might be a function of x, or y or z, or there might be some constant variables. For example users may want to solve an integration of A1 + (x/L)*A2, respect to "x" base on A1, A2 and L. Or they want to solve integral of Ax+by respect to y. The problem is I don't know which character user will use, so that i can define it as symbol. How could I do this?
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Accepted Answer
Steven Lord
on 23 Nov 2020
The symvar and str2sym functions listed (along with many others) on this documentation page may be of interest to you.
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Walter Roberson
on 24 Nov 2020
When you use str2func() then you get out a function handle for numeric evaluation, and you need to use integral() for numeric functions.
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Jan
on 24 Nov 2020
See how e.g. fzero and ode45 solves this problem. Here the function has 1 oder 2 variables which must be provided in a specific order. Constants are delivered to the function using anonymous functions. How the variables are called internally does not matter. The user simply provides the function handle and only the order of variables matter.
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