HP MLIB User's Guide Vol. 1 7th Ed.

402 HP MLIB User’s Guide
F_STBSV/F_DTBSV/F_CTBSV/F_ZTBSV Triangular banded solve
argument incx. If incx > 0 then x
i
is stored in
X (1 + (i - 1) x incx). If incx < 0 then x
i
is stored in
X (1 + (N - i) x |incx|). incx = 0 is an illegal value.
Output X The solution vector of the triangular system replaces
the input.