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Name: PGFUNX

Purpose: function defined by Y = F(X)

Category: GRAPHICS

File: pgplot.src

Author: T.J. Pearson

Use: see description below.

Description:

SUBROUTINE PGFUNX (FY, N, XMIN, XMAX, PGFLAG)
REAL FY
EXTERNAL FY
INTEGER N
REAL XMIN, XMAX
INTEGER PGFLAG

Draw a curve defined by the equation Y = FY(X), where FY is a
user-supplied subroutine.

Arguments:
FY (external real function): supplied by the user, evaluates
Y value at a given X-coordinate.
N (input) : the number of points required to define the
curve. The function FY will be called N+1 times.
If PGFLAG=0 and N is greater than 1000, 1000
will be used instead. If N is less than 1,
nothing will be drawn.
XMIN (input) : the minimum value of X.
XMAX (input) : the maximum value of X.
PGFLAG (input) : if PGFLAG = 1, the curve is plotted in the
current window and viewport; if PGFLAG = 0,
PGENV is called automatically by PGFUNX to
start a new plot with X limits (XMIN, XMAX)
and automatic scaling in Y.

Note: The function FY must be declared EXTERNAL in the Fortran
program unit that calls PGFUNX. It has one argument, the
x-coordinate at which the y value is required, e.g.
REAL FUNCTION FY(X)
REAL X
FY = .....
END

Note: This subroutine is only callable from Fortran, not from C.

Updates: Oct 16, 1998: JPT automatically extracted from source.