How do I obtain the original mapping after performing SYMRCM in MATLAB 7.1(R14SP3)?

I have written the following MATLAB code to perform inverse mapping using the SYMRCM function:

B = bucky; %original matrix

subplot(1,2,1), spy(B), title('B');

p = symrcm(B);

R = B(p,p); %matrix after SYMRCM

I want to obtain the mapping from B to R.

Answer 1

[MathWorks Support Team]

To obtain the original matrix after executing the SYMRCM function in MATLAB 7.1 (R14SP3) obtain the reverse mapping from the result of the SYMRCM function and apply it to the matrix generated from the result of the SYMRCM function.

Please refer the code below in MATLAB, in order to perform this operation:

B = bucky; %original matrix

p = symrcm(B);

R = B(p,p); %matrix after SYMRCM

% obtaining the original matrix from the matrix after SYMRCM

s=1:length(B);

e(p)=s;%map to original matrix.

G=R(e,e); 

subplot(1,2,1), spy(B), title('B');

subplot(1,2,2), spy(G), title('R(e,e)');