How to replace certain values in matrix ?

I have attached two .jpg files below. In first one i have values and some NaN values, in second file i.e 2_mass, i have matrix all filled with values. I want 2_mass.jpg file to show the NaN values at the same point as seen in 1_mass.jpg file and but other values should remain same. the final output should look like as shown in 3_mass.jpg

Answer 1

[Akira Agata]

Assuming A, B and C are your 1_mass, 2_mass and 3_mass matrix, the solution will be like:

 C = B;
 idx = isnan(A);
 C(idx) = NaN;

[Pritha Pande]

Thank you.