Converting a vector to multiple variables required as input for 'matlabFunction'.
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Taimoor Saif Talpur
il 24 Set 2012
Commentato: Graham Rowe
il 7 Nov 2020
I am converting symbolic function to a Matlab function using 'matlabFunction'.
For e.g.
syms x y
g=matlabFunction(x+y-1)
Output
g = @(x,y)x+y-1.0
The returned matlab function 'g' accepts individual variables like g(1,1). However, I want to give inputs as a vector, like,
input = [1 1]
g(input)
I get error 'Not enough input arguments.' I want to give input as a single vector because number of input in my actual function vary during run-time. Any idea how to convert a vector to multiple variable at run-time efficiently or any other solution.
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Risposta accettata
Andrei Bobrov
il 24 Set 2012
input = {1 1}
g(input{:})
5 Commenti
Leo Simon
il 6 Nov 2012
Thanks Walter
I could do everything without anonymous functions, but would prefer not to because of another infuriating matlab property which is that I can't define a function within an m-file, have to do it within a function. Should I just give up on passing an anonymous function to fsolve? I'm willing to do it the hard way if there is a hard way!
Walter Roberson
il 6 Nov 2012
I do not understand what you mean about can't define a function within an m-file ?
The code I show above involves passing anonymous functions to fsolve: it just uses a helper function which would be the same for all cases. The "g" that I reference in the expression call_on(g, x) is the anonymous function constructed via matlabFunction. The version that does not use this (invariant) helper function would need to use some nasty MATLAB behavior to fudge the temporary variable.
Più risposte (2)
Brad Carman
il 26 Gen 2018
The matlab documentation fails to mention that it's possible to set this up with matlabFunciton() itself. I've discovered that how you input the 'Vars' argument adjusts how the function is built. Using a vector input of variables for 'Vars' will give you what you want. See the following example:
syms x y
z = x+y;
Without vector input:
matlabFunction(z, 'Vars', {x, y})
function_handle with value:
@(x,y)x+y
With vector input:
matlabFunction(z, 'Vars', {[x, y]})
function_handle with value:
@(in1)in1(:,1)+in1(:,2)
3 Commenti
Ti Miller-Jackson
il 21 Ago 2019
Oh my gosh this works so well! You just saved me many hours. God bless you sir!
Graham Rowe
il 7 Nov 2020
This should be the accepted answer. So much more elegant than defining temporary variables that get created and then removed at run time.
Azzi Abdelmalek
il 24 Set 2012
Modificato: Azzi Abdelmalek
il 24 Set 2012
g = @(x,y)x+y-1.0
%g is a function of two inputs x and y, if you want one vector input
g=@(x) x(1)+x(2)-1.0
%then
g([2 3])
=4
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