Matrix with differential operators - HELP

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rodrigo
rodrigo 2013-10-9
回答： Lam Nguyen Van 2021-2-24
Hello all,
I need some help of you!
I have a matrix of deferential operators (like the image in attachment) and i want to write it in a Matlab notation in order to multiply it with a matrix of functions.
Anyone can help me ?
Thanks in advance

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回答（3 个）

Azzi Abdelmalek
Azzi Abdelmalek 2013-10-9
%Example
syms x y
f=@(h) [diff(h,y) diff(h,x);diff(h,x) -diff(h,y)]
h=2*x+3*y
f(h)
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Azzi Abdelmalek
Azzi Abdelmalek 2013-10-9
Maybe this is what you want
syms x y
f=@(h) [diff(h(1,1),y) diff(h(1,2),x);diff(h(2,1),x) -diff(h(2,2),y)]
h=[2*x+3*y 5*x+6*y;10*x+30*y 22*x-y]
f(h)
rodrigo
rodrigo 2013-10-9
More or less.
I have the matrix "h" with variable size. because that i have to multiply the operators matrix with expressions matrix, and not what that.
Any idea ?

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rodrigo
rodrigo 2013-10-10
Anyone can help me please ? Azzi's idea did not work for what want.
Thanks
  1 个评论
Cedric
Cedric 2013-10-16
编辑：Cedric 2013-10-16
What you want to achieve is still unclear to me. Do you need an "operator" which returns the analytical form of this matrix when applied to a function defined analytically/symbolically, or is it numeric?

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Lam Nguyen Van
Lam Nguyen Van 2021-2-24
Take a look: https://www.mathworks.com/matlabcentral/answers/36580-operator-matrix-for-matrix-differentiation
function dNdv = diffmtx(v,N)
% v -vector m x 1 - sym array
% N - matrix m x n - sym array
rz = arrayfun(@(ii)diff(N(ii,:),v(ii)),(1:numel(v)).','un',0);
dNdv = cat(1,rz{:});
end

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