OptionalkNumber of rows and columns of the triangular matrix to use (its top-left k x k block). Default: the number of columns of the matrix.
OptionaltransposeSolve t(r) y = x instead of r y = x. Default: false.
OptionalupperUse the upper triangle of the matrix. Default: true for backsolve, false for forwardsolve. R's upper.tri.
Options for backsolve and forwardsolve.