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Name: PGFUNY

Purpose: function defined by X = F(Y)

Category: GRAPHICS

File: pgplot.src

Author: T.J. Pearson

Use: see description below.

Description:

SUBROUTINE PGFUNY (FX, N, YMIN, YMAX, PGFLAG)
REAL FX
EXTERNAL FX
INTEGER N
REAL YMIN, YMAX
INTEGER PGFLAG

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

Arguments:
FX (external real function): supplied by the user, evaluates
X value at a given Y-coordinate.
N (input) : the number of points required to define the
curve. The function FX 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.
YMIN (input) : the minimum value of Y.
YMAX (input) : the maximum value of Y.
PGFLAG (input) : if PGFLAG = 1, the curve is plotted in the
current window and viewport; if PGFLAG = 0,
PGENV is called automatically by PGFUNY to
start a new plot with Y limits (YMIN, YMAX)
and automatic scaling in X.

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

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

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