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NAME
plcont - Contour plot
SYNOPSIS
plcont(f, nx, ny, kx, lx, ky, ly, clevel, nlevel, pltr, pltr_data)
DESCRIPTION
Draws a contour plot of the data in f[nx][ny], using the nlevel contour levels specified
by clevel. Only the region of the matrix from kx to lx and from ky to ly is plotted out
where all these index ranges are interpreted as one-based for historical reasons. A
transformation routine pointed to by pltr with a generic pointer pltr_data for additional
data required by the transformation routine is used to map indices within the matrix to
the world coordinates.
Redacted form: plcont(f, kx, lx, ky, ly, clevel, pltr, pltr_data) where (see above
discussion) the pltr, pltr_data callback arguments are sometimes replaced by a tr vector
with 6 elements; xg and yg vectors; or xg and yg matrices.
This function is used in examples 9, 14, 16, and 22.
ARGUMENTS
f (PLFLT_MATRIX(3plplot), input)
A matrix containing data to be contoured.
nx, ny (PLINT(3plplot), input)
The dimensions of the matrix f.
kx, lx (PLINT(3plplot), input)
Range of x indices to consider where 0 <= kx-1 < lx-1 < nx. Values of kx and lx
are one-based rather than zero-based for historical backwards-compatibility
reasons.
ky, ly (PLINT(3plplot), input)
Range of y indices to consider where 0 <= ky-1 < ly-1 < ny. Values of ky and ly
are one-based rather than zero-based for historical backwards-compatibility
reasons.
clevel (PLFLT_VECTOR(3plplot), input)
A vector specifying the levels at which to draw contours.
nlevel (PLINT(3plplot), input)
Number of contour levels to draw.
pltr (PLTRANSFORM_callback(3plplot), input)
A callback function that defines the transformation between the zero-based indices
of the matrix f and the world coordinates.For the C case, transformation functions
are provided in the PLplot library: pltr0(3plplot) for the identity mapping, and
pltr1(3plplot) and pltr2(3plplot) for arbitrary mappings respectively defined by
vectors and matrices. In addition, C callback routines for the transformation can
be supplied by the user such as the mypltr function in examples/c/x09c.c which
provides a general linear transformation between index coordinates and world
coordinates.For languages other than C you should consult the PLplot documentation
for the details concerning how PLTRANSFORM_callback(3plplot) arguments are
interfaced. However, in general, a particular pattern of callback-associated
arguments such as a tr vector with 6 elements; xg and yg vectors; or xg and yg
matrices are respectively interfaced to a linear-transformation routine similar to
the above mypltr function; pltr1(3plplot); and pltr2(3plplot). Furthermore, some of
our more sophisticated bindings (see, e.g., the PLplot documentation) support
native language callbacks for handling index to world-coordinate transformations.
Examples of these various approaches are given in examples/<language>x09*,
examples/<language>x16*, examples/<language>x20*, examples/<language>x21*, and
examples/<language>x22*, for all our supported languages.
pltr_data (PLPointer(3plplot), input)
Extra parameter to help pass information to pltr0(3plplot), pltr1(3plplot),
pltr2(3plplot), or whatever callback routine that is externally supplied.
AUTHORS
Many developers (who are credited at http://plplot.org/credits.php) have contributed to
PLplot over its long history.
SEE ALSO
PLplot documentation at http://plplot.org/documentation.php.
February, 2023 PLCONT(3plplot)