# How to write one universal function to evaluate many equations?

5 views (last 30 days)
Simon on 2 Jul 2023
Edited: Simon on 4 Jul 2023
I am working on verifying whether if equations are valid over a large data set. The challenge is that the number of equations to be verified is huge even though they are simple arithmetic equations and identities. In order to avoid writing a different function for each equation, I try to represent an equation as a 'model' and write only one universal function to eval each model. Here is a toy example to explain what I intend to do. My questions are 1.) whether if my approach is generally in right direction 2.) is there any way to avoid eval( ) in function foo( )? Thanks for your insights!
x = 7;
y = 3;
modelA = [x, y; "+", "-"];
foo(modelA)
ans = 4
z = -21;
modelB = [x, y, z; "-", "*", "=="];
foo(modelB)
ans = logical
1
function out = foo(model)
data = string(model(1,:));
operators = model(2,:);
a = strcat(operators, data);
out = eval(strcat(a{:}));
end
Paul on 2 Jul 2023
Comments can be stored using either the cell array or struct, if a cell array or struct with named fields happen to be the way to go.
C{1,1} = @(x,y,z) x - y == z;
C{1,2} = "this is the foo function";
C
C = 1×2 cell array
{@(x,y,z)x-y==z} {["this is the foo function"]}
% or
S.foo.eqn = @(x,y,z) x - y == z;
S.foo.comment = "this is the foo function";
S.foo
ans = struct with fields:
eqn: @(x,y,z)x-y==z comment: "this is the foo function"
Simon on 4 Jul 2023
Edited: Simon on 4 Jul 2023
@Paul I tried out your idea (structure of function handels). It works pretty well. Thanks!!

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