Hello, guys I am struggling with attaining stability values for u in solving the diffusion equation. The stability of u depends on the value of r from : Code (Text): D=1000; r0=1000; std=1.0; tau=1.0; IP=2500; %initial pressure % % Radial grid and inhomogeneous term nr=51; dr=r0/(nr-1); dr=50; for i=1:nr r(i)=(i-1)*dr+200; end Values of u doesn't oscillate and follow stable path from r at i=1 i.e. at r=200 as can be seen from the code above. Ideally u should vary with time and r exponentially as you will see from the graph in the code attached. However, when I replace 200 from the above equation with 1 to obtain u at r=1, the results become unstable and oscillates. So I would like to obtain variation of u from r=1 not from r=200 without osciallation Can you please help me to fix that problem. All necessary codes are attached.