how can I vectorize my code when multiple variables are present
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Hi All,
I'm trying to figure out how to vectorize my code when multiple variables are present. The following is the toy model with odes for 2 variables (Please note the code may not make much sense, in my real system variables w and u are coupled. Also, in the actual system the number of variables in the model is uder-defined. For this reason, I am looping through the variables in the for-loop).
global mat1 mat2 k nvar var npts
k = 2;
nvar =2;
var = ["w", "x"];
npts=10;
mat1=[
1 -2 1 0 0 0 0 0 0 0;
0 1 -2 1 0 0 0 0 0 0;
0 0 1 -2 1 0 0 0 0 0;
0 0 0 1 -2 1 0 0 0 0;
0 0 0 0 1 -2 1 0 0 0;
0 0 0 0 0 1 -2 1 0 0;
0 0 0 0 0 0 1 -2 1 0;
0 0 0 0 0 0 0 1 -2 1;
];
mat2 = [
1 -1 0 0 0 0 0 0 0 0;
0 1 -1 0 0 0 0 0 0 0;
0 0 1 -1 0 0 0 0 0 0;
0 0 0 1 -1 0 0 0 0 0;
0 0 0 0 1 -1 0 0 0 0;
0 0 0 0 0 1 -1 0 0 0;
0 0 0 0 0 0 1 -1 0 0;
0 0 0 0 0 0 0 1 -1 0;
];
w0 = [2 0 0 0 0 0 0 0 0 0]';
x0 = [1 0 0 0 0 0 0 0 0 0]';
z0 = [w0; x0];
tspan = 0:0.01:0.5;
f0 = fun(0, z0);
joptions = struct('diffvar', 2, 'vectvars', 2, 'thresh', 1e-8, 'fac', []);
J = odenumjac(@fun,{0 z0}, f0, joptions);
sparsity_pattern = sparse(J~=0.);
options = odeset('Stats', 'on', 'Vectorized', 'on'); %, 'JPattern', sparsity_pattern);
ttic = tic();
[t, sol] = ode15s(@(t,z) fun(t,z), tspan , z0, options);
ttoc = toc(ttic)
fprintf('runtime %f seconds ...\n', ttoc)
plot(t, sol)
function Zstruct = get_Zstruct(z)
global nvar var npts
temp = reshape(z, npts, []);
for i = 1:nvar
Zstruct.(var(i)) = temp(:,i);
end
end
function dz = fun(t,z)
global nvar var mat1 mat2
fprintf('size of z %d %d...\n', size(z))
dz = zeros(size(z), 'like', z);
Zstruct = get_Zstruct(z);
F =[];
for i = 1:nvar
x = Zstruct.(var(i));
f = zeros(size(x), 'like', x);
f(1,:) = 0;
f(2:9,:) = mat1*x + mat2*x;
f(10,:) = 2*(x(end-1) - x(end));
end
F(:,:) = vertcat(F,f);
end
I tried to check the size of z and it inconsistent for different function calls.
size of z 20 1...
size of z 20 20...
size of z 20 1...
size of z 20 1...
:
size of z 20 1...
size of z 20 1...
size of z 20 1...
size of z 20 20...
I'm sure the mistake is in the function Zstruct = get_Zstruct(z). I'm not sure how to vectorize here. Could someone please help me with this?
3 个评论
Deepa Maheshvare
2021-2-22
Walter Roberson
2021-2-23
for i = 1:nvar
Zstruct.(var(i)) = temp(:,i);
end
cell2struct() instead of the loop.
Deepa Maheshvare
2021-2-23
编辑：Deepa Maheshvare
2021-2-23
回答（1 个）
darova
2021-2-22
0 个投票
Try to remove parenthesis
1 个评论
Deepa Maheshvare
2021-2-23
编辑：Deepa Maheshvare
2021-2-23
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