`ztrmv:`procedure`xTRMV`performs matrix-vector multiply-add operation of the form`y := alpha*op( A )*x`, where`op ( A ) = A`or`op ( A ) = A'``ALPHA`and`BETA`are scalars, and`A`is an`N x N`upper or lower triangular matrix.`X`is a vector of length`(1 + (n - 1) * abs(INCX))`.