how can i substitute elements of a symbolic matrix with arrays of numbers?

Hi,

i have a symbolic matrix

   A(2*3) = [a_1 a_2 a_3; a_4 a_5 a_6];

also i have 20*1 arrays of numbers. such as

b_1(20,1),b_2(20,1),b_3(20,1),b_4(20,1),b_5(20,1).

i need to substitute elements of symbolic matrix with elements of array one at a time, lets say

a_1=b_1(1,1),a_2=b_2(1,1),a_3=b_3(1,1),a_4=b_4(1,1),a_5=b_5(1,1)

and keep substituting to the last elements of a_1=b_1(20,1), ....

can someone please give me a hint?

thank you in advance

[Walter Roberson]

What size of output are you expecting?

Answer 1

[Walter Roberson]

arrayfun(@(K) subs(A, A, [b_1(K), b_2(K), b_3(K); b_4(K), b_5(K), b_6(K)]), 1:length(b_1), 'Uniform', 0)

Note that the substituting vector, [b_1(K), b_2(K), b_3(K); b_4(K), b_5(K), b_6(K)] must be the same shape as the vector of variables, A, for this to work.

An easier way to handle this would be

mat2cell( reshape([b_1, b_2, b_3, b_4, b_5, b_6], [], 3, 2), ones(1, length(b_1)), 3, 2 )

since really your A is not participating in the process.

[Joseph]

i tried this but it's giving me the below errors:

Error using sym/subs>normalize (line 201) OLD and NEW must have the same number of entries.

Error in sym/subs>mupadsubs (line 136) [X2,Y2,symX,symY] = normalize(X,Y); %#ok

Error in sym/subs (line 124) G = mupadsubs(F,X,Y);

Error in @(k)subs(A,A,[J_up_00(k),S(k),N_up_00(k),omega_up_00(k),sigma_00_up(k),lambda_up_00(k)])

Error in Hundscase_a_int (line 308) arrayfun(@(k) subs(A, A, [J_up_00(k), S(k), N_up_00(k), omega_up_00(k), sigma_00_up(k), lambda_up_00(k)]), 1:length(J_up_00), 'Uniform', 0);

in order to clarify more, i should say that these matrices actually are transformation matrices that transforms elements of one array to the new array. i upload a photo capture of this transformation, hopefully it'll clarify the process more. each element of these matrices are 20*1 array that i need to substitute in the matrix one at a time and do the transformation.note that the name of elements are different.

thankyou

[Walter Roberson]

As I wrote,

Note that the substituting vector, [b_1(K), b_2(K), b_3(K); b_4(K), b_5(K), b_6(K)] must be the same shape as the vector of variables, A, for this to work.

You did not do that: you used a replacement vector 1 x 6 instead of a 2 x 3 replacement vector.

arrayfun(@(k) subs(A, A, [J_up_00(k), S(k), N_up_00(k); omega_up_00(k), sigma_00_up(k), lambda_up_00(k)]), 1:length(J_up_00), 'Uniform', 0)

Note the semi-colon

[Joseph]

thanks for your help.

just one more question, since now A is a cell array that contains 2*3 symbolic matrices, how to convert this to a numerical matrix in order to use it in a for loop? (i need to pick one 2*3 matrix and use it in an equation as a conversion matrix such c=b(2*3)*a in which a is initial value and c is final value. i need to do this until i get array of final values which is the same size as A). also i should say that i have 5 rrays like A that i need to multiply in order to get the final values. for better understanding of the process, i attached the same photo capture in this comment.i hope i could clear it up. thank you

[Walter Roberson]

A will not be a cell array, but the output of the arrayfun will be a cell array. Do not confuse things by assigning it to the same variable name.

You can access members of the cell array using {} indexing.

subs_A = arrayfun(@(k) subs(A, A, [J_up_00(k), S(k), N_up_00(k); omega_up_00(k), sigma_00_up(k), lambda_up_00(k)]), 1:length(J_up_00), 'Uniform', 0);

for K = 1 : numel(subs_A)
  this_A = subs_A{K};
  c = b * this_A;
  not sure what you want to do with c
end

But it sort of sounds to me as if you want

subs_A = arrayfun(@(k) subs(A, A, [J_up_00(k), S(k), N_up_00(k); omega_up_00(k), sigma_00_up(k), lambda_up_00(k)]), 1:length(J_up_00), 'Uniform', 0);
c = cellfun( @(this_A) b * this_A, subs_A, 'Uniform', 0);

[Walter Roberson]

If you have multiple cell arrays that you want to multiply corresponding values of, then for example

c = cellfun( @(this_A1, this_A2, this_A3) b * this_A, subs_A1, subs_A2, subs_A3, 'Uniform', 0);

where subs_A1, subs_A2, subs_A3 are the cell arrays whose corresponding elements are to be multiplied.