MATLAB: Vectorize a code that finds the roots of polynomials stored in matrices

Question

I need some tips on how to vectorize a code that finds the roots of polynomials stored in matrices. What I have is a multidimensional array that contains 100 matrices of 100-by-3 size. I'm pasting the code below

 one = ones ( 100, 100 );
 poly.struc = reshape( [ one; gr_fac1; - gr_fac2 ], 100, 3, [] ); 
 poly_roots_select = zeros ( 100, 100);
 for j = 1:1:100
 poly_matrices = poly.struc ( :, :, j );
    for i = 1:1:100
      poly_select = poly_matrices ( i, : );
      poly_roots = roots ( poly_select );
      poly_roots_select ( i , j)  =  poly_roots ( real ( poly_roots) > 0 , 1 ) ; 
    end
 end

I would like to remove both for loops. At minimum I like to be able to access the matrices stored in poly.struc array without putting a loop for this. Is there also any other way to be able to pass a row vectors from a matrix to roots function without needing a loop?

Thanks in advance

Answer 1

The roots function only accepts vectors.

You may speed up your code by getting rid of the two intermediate variables poly_matrices and poly_select:

 for j = 1:1:100
    for i = 1:1:100
      poly_roots = roots ( poly.struc ( i, :, j ) );
      poly_roots_select ( i , j ) = poly_roots ( real ( poly_roots) > 0 , 1 ) ; 
    end
 end