%N pgfunt %F $MIR/src/pgfunt.f
%D Function defined by X = F(T), Y = G(T)
%B
      SUBROUTINE PGFUNT (FX, FY, N, TMIN, TMAX, PGFLAG)
      REAL FX, FY
      EXTERNAL FX, FY
      INTEGER N
      REAL TMIN, TMAX
      INTEGER PGFLAG

 Draw a curve defined by parametric equations X = FX(T), Y = FY(T).

 Arguments:
  FX     (external real function): supplied by the user, evaluates
                    X-coordinate.
  FY     (external real function): supplied by the user, evaluates
                    Y-coordinate.
  N      (input)  : the number of points required to define the
                    curve. The functions FX and FY will each be
                    called N+1 times.
  TMIN   (input)  : the minimum value for the parameter T.
  TMAX   (input)  : the maximum value for the parameter T.
  PGFLAG (input)  : if PGFLAG = 1, the curve is plotted in the
                    current window and viewport; if PGFLAG = 0,
                    PGENV is called automatically by PGFUNT to
                    start a new plot with automatic scaling.

 Note: The functions FX and FY must be declared EXTERNAL in the
 Fortran program unit that calls PGFUNT.
