This is my Matlab code. I am trying to simply substitute the M=[0 0 1] into n like this n1=0 n2=0 n3=1 but the answer comes without the substitution happening. What should I do to fix this?
M=zeros(1,3)
M(1,3) = 1;
syms n [1 5]
f=@(n) n1+6*n2+2*n3
a=f(M)
---------
n =
[ n1, n2, n3]
a =
n1 + 6n2 + 2n3
How can I get
a= 0+0+2
if the substitution happens

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Walter Roberson
Walter Roberson am 19 Feb. 2021

1 Stimme

M=zeros(1,3)
M = 1×3
0 0 0
M(1,3) = 1;
syms n [1 5]
f = matlabFunction(n1+6*n2+2*n3, 'vars', {n})
f = function_handle with value:
@(in1)in1(:,1)+in1(:,2).*6.0+in1(:,3).*2.0
a=f(M)
a = 2

2 Kommentare

Note: the 'vars', {n} is important there.
M=zeros(1,3)
M = 1×3
0 0 0
M(1,3) = 1;
syms n [1 5]
f = matlabFunction(n1+6*n2+2*n3)
f = function_handle with value:
@(n1,n2,n3)n1+n2.*6.0+n3.*2.0
Notice it created a function that expects three separate input variables instead of a vector of values
a=f(M)
Not enough input arguments.

Error in symengine>@(n1,n2,n3)n1+n2.*6.0+n3.*2.0
Walter Roberson
Walter Roberson am 19 Feb. 2021
https://www.mathworks.com/matlabcentral/answers/750054-matlab-function-with-multiple-sym-variables?s_tid=srchtitle

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