please fix and solve the issue my matlab code project : $\%$Mike$\_$id$\_$Project$\_$main.m : I dont not have to use structures, and it does not allow $3$ separate assignments on the "trials" variable.

You can just create $3$ different variable arrays for m$,$ k$,$ and c$,$ and call m$($i$),$ k$($i$),$ and c$($i$)$ during each trial run.

For the animation part, please remember that since the framerate is $30$ while dt is $1/300,$ that would mean $1$ frame every $10$ iterations.

Therefore, on line $142,$ the for loop should state a manual stepsize of $10.$ : $\%$ MataJocelyn$\_900585559\_$Project$\_$main.m clear; close all; clc; $\%$ Trial Parameters trials $=[...$ struct$(\text{'}$mass$\text{'},3,\text{'}$k$\text{'},200,\text{'}$c$\text{'},2)$; struct$(\text{'}$mass$\text{'},4,\text{'}$k$\text{'},50,\text{'}$c$\text{'},45)$; struct$(\text{'}$mass$\text{'},5,\text{'}$k$\text{'},125,\text{'}$c$\text{'},50)]$; $\%$ Simulation Parameters t$0=0$; $\%$ Initial time tf $=10$; $\%$ Final time dt $=1/300$; $\%$ Time step fps $=30$; $\%$ Frames per second x$0=1$; $\%$ Initial position v$0=0$; $\%$ Initial velocity a$0=2\mathrm{.}5$; $\%$ Forcing amplitude $\%$ Iterate through trials for trial $=1$:length$($trials$)\%$ Extract trial parameters m $=$ trials$($trial$).$mass; k $=$ trials$($trial$).$k; c $=$ trials$($trial$).$c; $\%$ Time array t $=$ t$0$:dt:tf; $\%$ Preallocate arrays for position and velocity x$\_$homogeneous$\_$euler $=$ zeros$($size$($t$))$; v$\_$homogeneous$\_$euler $=$ zeros$($size$($t$))$; x$\_$inhomogeneous$\_$euler $=$ zeros$($size$($t$))$; v$\_$inhomogeneous$\_$euler $=$ zeros$($size$($t$))$; x$\_$homogeneous$\_$rk $=$ zeros$($size$($t$))$; v$\_$homogeneous$\_$rk $=$ zeros$($size$($t$))$; x$\_$inhomogeneous$\_$rk $=$ zeros$($size$($t$))$; v$\_$inhomogeneous$\_$rk $=$ zeros$($size$($t$))$; $\%$ Set initial conditions x$\_$homogeneous$\_$euler$(1)=0$; v$\_$homogeneous$\_$euler$(1)=$ v$0$; x$\_$inhomogeneous$\_$euler$(1)=$ x$0$; v$\_$inhomogeneous$\_$euler$(1)=$ v$0$; x$\_$homogeneous$\_$rk$(1)=$ x$0$; v$\_$homogeneous$\_$rk$(1)=$ v$0$; x$\_$inhomogeneous$\_$rk$(1)=$ x$0$; v$\_$inhomogeneous$\_$rk$(1)=$ v$0$; $\%$ Simulate for each time step for i $=2$:length$($t$)\%$ Homogeneous $($F$($t$)=0)[$x$\_$homogeneous$\_$euler$($i$),$ v$\_$homogeneous$\_$euler$($i$)]=$ VibrationPosition$(...$ x$\_$homogeneous$\_$euler$($i$-1),$ v$\_$homogeneous$\_$euler$($i$-1),$ m$,$ k$,$ c$,0,$ dt$,1)$; $[$x$\_$homogeneous$\_$rk$($i$),$ v$\_$homogeneous$\_$rk$($i$)]=$ VibrationPosition$(...$ x$\_$homogeneous$\_$rk$($i$-1),$ v$\_$homogeneous$\_$rk$($i$-1),$ m$,$ k$,$ c$,0,$ dt$,2)$; $\%$ Inhomogeneous $($F$($t$)=$ a$0*$ sin$($t$/(2*$pi$)))$ f$\_$inhom $=$ a$0*$ sin$($t$($i$)/(2*$ pi$))$; $[$x$\_$inhomogeneous$\_$euler$($i$),$ v$\_$inhomogeneous$\_$euler$($i$)]=$ VibrationPosition$(...$ x$\_$inhomogeneous$\_$euler$($i$-1),$ v$\_$inhomogeneous$\_$euler$($i$-1),$ m$,$ k$,$ c$,$ f$\_$inhom, dt$,1)$; $[$x$\_$inhomogeneous$\_$rk$($i$),$ v$\_$inhomogeneous$\_$rk$($i$)]=$ VibrationPosition$(...$ x$\_$inhomogeneous$\_$rk$($i$-1),$ v$\_$inhomogeneous$\_$rk$($i$-1),$ m$,$ k$,$ c$,$ f$\_$inhom, dt$,2)$; end $\%$ Plotting results figure$(\text{'}$Position$\text{'},[100,100,1200,600])$; $\%$ Euler Method Subplot subplot$(1,2,1)$; plot$($t$,$ x$\_$homogeneous$\_$euler, $\text{'}$b$-\text{'},$ 'LineWidth', $1\mathrm{.}5)$; title$([\text{'}$Trial $\text{'}$ num$2$str$($trial$)\text{'}-$ Homogeneous $($Euler$)\text{'}])$; xlabel$(\text{'}$Time $($s$)\text{'})$; ylabel$(\text{'}$Position $($m$)\text{'})$; grid on; subplot$(1,2,2)$; plot$($t$,$ x$\_$inhomogeneous$\_$euler, $\text{'}$r$-\text{'},$ 'LineWidth', $1\mathrm{.}5)$; title$([\text{'}$Trial $\text{'}$ num$2$str$($trial$)\text{'}-$ Inhomogeneous $($Euler$)\text{'}])$; xlabel$(\text{'}$Time $($s$)\text{'})$; ylabel$(\text{'}$Position $($m$)\text{'})$; grid on; $\%$ Save figure saveas$($gcf$,[\text{'}$Trial$\_\text{'}$ num$2$str$($trial$)\text{'}\_$Euler.fig'$])$; close; $\%$ RK$4$ Method Subplot figure$(\text{'}$Position$\text{'},[100,100,1200,600])$; subplot$(1,2,1)$; plot$($t$,$ x$\_$homogeneous$\_$rk$,\text{'}$b$-\text{'},$ 'LineWidth', $1\mathrm{.}5)$; title$([\text{'}$Trial $\text{'}$ num$2$str$($trial$)\text{'}-$ Homogeneous $($RK$4)\text{'}])$; xlabel$(\text{'}$Time $($s$)\text{'})$; ylabel$(\text{'}$Position $($m$)\text{'})$; grid on; subplot$(1,2,2)$; plot$($t$,$ x$\_$inhomogeneous$\_$rk$,\text{'}$r$-\text{'},$ 'LineWidth', $1\mathrm{.}5)$; title$([\text{'}$Trial $\text{'}$ num$2$str$($trial$)\text{'}-$ Inhomogeneous $($RK$4)\text{'}])$; xlabel$(\text{'}$Time $($s$)\text{'})$; ylabel$(\text{'}$Position $($m$)\text{'})$; grid on; $\%$ Save figure saveas$($gcf$,[\text{'}$Trial$\_\text{'}$ num$2$str$($trial$)\text{'}\_$RK$4.$fig'$])$; close; $\%$ Animation Generation figure$(\text{'}$Position$\text{'},[100,100,1200,600])$; $\%$ Homogeneous Response Animation subplot$(1,2,1)$; h$1=$ animatedline$(\text{'}$Color$\text{'},\text{'}$b$\text{'},$ 'LineWidth', $2)$; title$([\text{'}$Trial $\text{'}$ num$2$str$($trial$)\text{'}-$ Homogeneous'$])$; xlabel$(\text{'}$Time $($s$)\text{'})$; ylabel$(\text{'}$Position $($m$)\text{'})$; xlim$([$t$0$ tf$])$; ylim$([$min$([$x$\_$homogeneous$\_$euler, x$\_$homogeneous$\_$rk$])-0\mathrm{.}5,$ max$([$x$\_$homogeneous$\_$euler, x$\_$homogeneous$\_$rk$])+0\mathrm{.}5])$; grid on; $\%$ Inhomogeneous Response Animation subplot$(1,2,2)$; h$2=$ animatedline$(\text{'}$Color$\text{'},\text{'}$r$\text{'},$ 'LineWidth', $2)$; title$([\text{'}$Trial $\text{'}$ num$2$str$($trial$)\text{'}-$ Inhomogeneous'$])$; xlabel$(\text{'}$Time $($s$)\text{'})$; ylabel$(\text{'}$Position $($m$)\text{'})$; xlim$([$t$0$ tf$])$; ylim$([$min$([$x$\_$inhomogeneous$\_$euler, x$\_$inhomogeneous$\_$rk$])-0\mathrm{.}5,$ max$([$x$\_$inhomogeneous$\_$euler, x$\_$inhomogeneous$\_$rk$])+0\mathrm{.}5])$; grid on; $\%$ Create video writer v $=$ VideoWriter$([\text{'}$Mike$\_$id$\_$video$\_\text{'}$ num$2$str$($trial$)],$ 'MPEG$-$