Using Mathlab

$\%$ Given symbolic variables

syms a b x y xel yel;

$\%$ Define the function for y $($top curve of the rectangle$)$

$\%$ Define the limits of integration

x$\_$min $=0$;

x$\_$max $=$ a;

y$\_$min $=0$;

y$\_$max $=$ b;

$\%$ Compute the area of the rectangle

Area $=$ int$($int$(1,$ y$,$ y$\_$min, y$\_$max$),$ x$,$ x$\_$min, x$\_$max$)$;

$\%$ Compute the x$-$coordinate of the centroid

x$\_$centroid $=(1/$Area$)*$ int$($int $($x$,$ y$,$ y$\_$min, y$\_$max$),$ x$,$ x$\_$min, x$\_$max$)$;

$\%$ Compute the y$-$coordinate of the centroid

y$\_$centroid $=(1/$Area$)**$ int$($int$($y$,$ y$,$ y$\_$min, y$\_$max$),$ x$,$ x$\_$min, x$\_$max$)$;

$\%$ Display the results

disp$([\text{'}$Centroid $($x$)$: $\text{'},$ char$($x$\_$centroid$)])$;

disp$([\text{'}$Centroid $($y$)$: $\text{'},$ char$($y$\_$centroid$)])$;

Command Windowsyms requires Symbolic Math Toolbox.

Error in untitled$4($line $2)$

syms a b x y xel yel;

Help me to fix this mistake?