The function y is defined as

space space y equals open curly brackets table attributes columnalign left end attributes row cell table row $0$ cell text for end text x less than $0$ end cell row cell fraction numerator $2$ left parenthesis x plus $1$ right parenthesis cos left parenthesis $3$ x right parenthesis over denominator x squared plus $1$ end fraction end cell cell text for end text $0$ less or equal than x less than $0\mathrm{.}9$ end cell end table end cell row cell table row cell fraction numerator $3$ x e to the power of negative $0\mathrm{.}2$ x end exponent over denominator x squared plus $1$ end fraction end cell cell text for end text x greater or equal than $0\mathrm{.}9$ end cell end table end cell end table close

Using a for loop or otherwise,

$($a$)$ Determine the values of y in a vector called z for x values from $-2$ to $2$ in steps of $0\mathrm{.}2.$ Display the values of vector z$.$

$($b$)$ Determine and display the sum of values of the vector z$.$