Write a Matlab script to build a lower triangular matrix of dimension $8$ having $-2$

on the main diagonal and $3$ on the second lower diagonal. Build another matrix by first

interchanging the third and sixth row of the previous matrix, and then interchanging the

second and eighth column.

Write a Matlab script for evaluating function $y=f(x)=xsin(2x)$ on the interval

$0,1$ at $n=21$ equally spaced points $(20$ subintervals$).$

a$)$ Use a "for$-$loop" to evaluate the function element$-$wise. Display the result using "plot".

b$)$ Use only vector operations $($w$/$o any loops$)$ to evaluate the function. Display the result

using "plot".