finite difference method remove for loop

Hello all

I have a complex for nested loop need to vectorization, the code I posted below is a piece of my code to calculate finite difference equation. Because my execution time takes too long so I need to improve it. Please give me any advice to reduce execution time. Thanks for any help from you, all

if true
% code
loopVal1 = 14;
loopVal2 = 12;
loopVal3 = 20;
for n = 1:loopVal1
      for nx = 2:loopVal2- 1
          for ny = 2:loopVal3- 1
              n = (ny - 1)*loopVal2+ nx;
              nm = n + (nc - 1)*loopVal2*loopVal3;
              g_o(nm) =-coffi(n,nc).*(heatNext(1, n, nc)-heat(1, n, nc))./dt + 0.5.*((k(n, nc).*(heat(1, n  + 1, nc) - 2.*heat(1, n, nc) + heat(1, n  - 1, nc));
              matrix(nm, nm - 1) = -coffi1(n,nc)./(2.*dx.^2);
              matrix(nm, nm - loopVal2) = -coffi1(n,nc)./(2.*dy.^2);
              matrix(nm, nm + loopVal2) = -coffi1(n,nc)./(2.*dy.^2);
              matrix(nm, nm) = coffi(n,nc)./dt +  heatNext(1, n - loopVal2, nc))/dy^2;
              Matrix(nm, nm + 1) = -coffi1(n,nc)/(2*dx^2);

           end
      end
  end