Matrix Stack Routines.

pushmatrix()

Save the current transformation matrix on the matrix stack.

    Fortran:
         subroutine pushmatrix

    C:
         pushmatrix()

    Pascal:
         procedure PushMatrix

popmatrix()

Retrieve the last matrix pushed and make it the current transformation matrix.

    Fortran:
         subroutine popmatrix

    C:
         popmatrix()

    Pascal:
         procedure PopMatrix