$($a$)$ Create an evenly spaced vector of values from $1$ to $20$ in increments of $1.$

Assign the resulting vector to a variable named a$.$

$($b$)$ Create a vector of values from zero to $2$pi in increments of pi$/10.$

Assign the resulting vector to a variable named b$.$

$($c$)$ Create a vector containing $15$ values, evenly spaced between $4$ and $20.$

Assign the resulting vector to a variable named c$.$

$($d$)$ Create a vector containing $4$ values, spaced logarithmically between $10$ and $1000.$

Assign the resulting vector to a variable named d$.$ in matlab