$\%$ File name: fdtd$\_$free.m$\%$ Plots E and H components of Gaussian pulse in a free space $\%$ after some number of time steps using FDTD method$\%$ No animationclear all;N$\_$h $=200$; $\%$ number of z$-$cellsN$\_$t $=100$; $\%$ number of time stepstime $=0\mathrm{.}0$;E$\_$x $=$ zeros$($N$\_$h$,1)$; $\%$ Initialize fields to zero at all pointsH$\_$y $=$ zeros$($N$\_$h$,1)$;t$\_$zero $=40\mathrm{.}0$; $\%$ center of incident pulsewidth $=12$; $\%$ width of the incident pulsetic; $\%$ start timerfor istep $=1$:N$\_$t $\%$ time loop time $=$ time $+1$; pulse $=$ exp$(-0\mathrm{.}5*(($t$\_$zero $-$ time$)/$width$)^2)$; $\%$ Gaussian pulse for i $=2$:N$\_$h E$\_$x$(120)=$ pulse; $\%$ location of initial pulse E$\_$x$($i$)=$ E$\_$x$($i$)-0\mathrm{.}5*($H$\_$y$($i$)-$ H$\_$y$($i$-1))$; end $\%$ for i $=1$:$($N$\_$h $-1)$ H$\_$y$($i$)=$ H$\_$y$($i$)-0\mathrm{.}5*($E$\_$x$($i$+1)-$ E$\_$x$($i$))$; endendtoc $\%$ measure elapsed time since last call to ticsubplot$(2,1,1)$; plot$($E$\_$x$)$ylabel$(\text{'}$E$\_$x$\text{'})$; xlabel$(\text{'}$FDTD cells'$)$axis$([0200-11])$subplot$(2,1,2)$; plot$($H$\_$y$)$ylabel$(\text{'}$H$\_$y$\text{'})$; xlabel$(\text{'}$FDTD cells'$)$axis$([0200-11])$pause

close allElaborate the code of $1d$ fdtd that we write at lecture.Your explanation must have the followings;