$\%$ Define coefficient matrix A and the initial temperature vector T A $=$ diag$($ones$($nx$-1,1)*-2*$ alpha $*$ dt $/$ dx$^2,0)...+$ diag$($ones$($nx$-2,1)*$ alpha $*$ dt $/$ dx$^2,1)...+$ diag$($ones$($nx$-2,1)*$ alpha $*$ dt $/$ dx$^2,-1)$; $\%$ Loop over time for implicit method for t $=1$:total$\_$time T$\_$new $=$ A $\backslash$ T; $\%$ Solve the linear system T $=$ T$\_$new; $\%$ Update temperature distribution if mod$($t$,3600*5)==0\%$ Checkpoints at every $5$ hours in seconds disp$($T$)$; $\%$ Display or store temperatures end end