How to generate a matrix from specific outputs from a MATLAB file?

Hi, the file test_modified.m generates a set of values for "SP" and "grad". How can I extract the calculated grad values which appear as:

2.1146

1.5751

1.5751

2.7125

and form a matrix as

2.1146 & 1.5751

1.5751 & 2.7125

automatically?

Thanks

Answer 1

[Voss]

Each grad is a 2x2 matrix; it's not clear from the question what size you want the final grad array to be, so here's one way to put them all in a 2x2xN array:

N = 4; % number of experiments

result = zeros(2*N,1); % pre-allocate result arrays
grad_all = zeros(2,2,N);

dt=0.01;
T=1;
k=[5;1];
y0_all = [2 1 1 4; 1 1 0 1];

for ii = 1:N
    y0 = y0_all(:,ii);
    [SP,grad]=enzyme(y0,k,dt,T);
    result((ii-1)*2+[1 2]) = y0-SP;
    grad_all(:,:,ii) = grad;
end

disp(grad_all)

(:,:,1) =

   -0.2244    0.5130
    0.2244   -0.5130


(:,:,2) =

   -0.1137    0.3601
    0.1137   -0.3601


(:,:,3) =

   -0.0548    0.2092
    0.0548   -0.2092


(:,:,4) =

   -0.4028    0.5262
    0.4028   -0.5262

Answer 2

[Taylor]

a = [2.1146 1.5751 1.5751 2.7125]'

a = 4×1

2.1146 1.5751 1.5751 2.7125

b = reshape(a,[2 2])

b = 2×2

2.1146 1.5751 1.5751 2.7125

[Sergio]

This would work on those generated values, but if I change the experiment data, those values have to be remade manually. The idea was to generate this from the file data, so a matrix is given automatically whatever the experiment values are.

[Dyuman Joshi]

Then modify the reshape() call accordingly/as per need.

[Sergio]

@Dyuman Joshi How?

reshape(M, 2, 2)

but how to call on the grad values?

[Stephen23]

" but how to call on the grad values?"

Just do the same for GRAD as I showed you for SP:

https://www.mathworks.com/matlabcentral/answers/2095876-how-to-extract-data-from-a-file-and-form-a-column-vector#answer_1427096

Then RESHAPE after the loop.