// Contour plot demo.
//
// This file is part of PLplot.
//
// PLplot is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published
// by the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// PLplot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with PLplot; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
//
//
#include "plcdemos.h"
#define XPTS 35 // Data points in x
#define YPTS 46 // Data points in y
#define XSPA 2. / ( XPTS - 1 )
#define YSPA 2. / ( YPTS - 1 )
// polar plot data
#define PERIMETERPTS 100
#define RPTS 40
#define THETAPTS 40
// potential plot data
#define PPERIMETERPTS 100
#define PRPTS 40
#define PTHETAPTS 64
#define PNLEVEL 20
static PLFLT clevel[11] =
{ -1., -.8, -.6, -.4, -.2, 0, .2, .4, .6, .8, 1. };
// Transformation function
PLFLT tr[6] =
{ XSPA, 0.0, -1.0, 0.0, YSPA, -1.0 };
// pltr_data is unused so mark it with the PL_UNUSED macro
static void
mypltr( PLFLT x, PLFLT y, PLFLT *tx, PLFLT *ty, void * PL_UNUSED( pltr_data ) )
{
*tx = tr[0] * x + tr[1] * y + tr[2];
*ty = tr[3] * x + tr[4] * y + tr[5];
}
static void polar( void )
//polar contour plot example.
{
int i, j;
PLcGrid2 cgrid2;
PLFLT **z;
PLFLT px[PERIMETERPTS], py[PERIMETERPTS];
PLFLT t, r, theta;
PLFLT lev[10];
plenv( -1., 1., -1., 1., 0, -2 );
plcol0( 1 );
//Perimeter
for ( i = 0; i < PERIMETERPTS; i++ )
{
t = ( 2. * M_PI / ( PERIMETERPTS - 1 ) ) * (PLFLT) i;
px[i] = cos( t );
py[i] = sin( t );
}
plline( PERIMETERPTS, px, py );
//create data to be contoured.
plAlloc2dGrid( &cgrid2.xg, RPTS, THETAPTS );
plAlloc2dGrid( &cgrid2.yg, RPTS, THETAPTS );
plAlloc2dGrid( &z, RPTS, THETAPTS );
cgrid2.nx = RPTS;
cgrid2.ny = THETAPTS;
for ( i = 0; i < RPTS; i++ )
{
r = i / (PLFLT) ( RPTS - 1 );
for ( j = 0; j < THETAPTS; j++ )
{
theta = ( 2. * M_PI / (PLFLT) ( THETAPTS - 1 ) ) * (PLFLT) j;
cgrid2.xg[i][j] = r * cos( theta );
cgrid2.yg[i][j] = r * sin( theta );
z[i][j] = r;
}
}
for ( i = 0; i < 10; i++ )
{
lev[i] = 0.05 + 0.10 * (PLFLT) i;
}
plcol0( 2 );
plcont( (PLFLT_MATRIX) z, RPTS, THETAPTS, 1, RPTS, 1, THETAPTS, lev, 10,
pltr2, (void *) &cgrid2 );
plcol0( 1 );
pllab( "", "", "Polar Contour Plot" );
plFree2dGrid( z, RPTS, THETAPTS );
plFree2dGrid( cgrid2.xg, RPTS, THETAPTS );
plFree2dGrid( cgrid2.yg, RPTS, THETAPTS );
}
//--------------------------------------------------------------------------
// f2mnmx
//
// Returns min & max of input 2d array.
//--------------------------------------------------------------------------
static void
f2mnmx( PLFLT **f, PLINT nx, PLINT ny, PLFLT *fnmin, PLFLT *fnmax )
{
int i, j;
*fnmax = f[0][0];
*fnmin = *fnmax;
for ( i = 0; i < nx; i++ )
{
for ( j = 0; j < ny; j++ )
{
*fnmax = MAX( *fnmax, f[i][j] );
*fnmin = MIN( *fnmin, f[i][j] );
}
}
}
static void potential( void )
//shielded potential contour plot example.
{
int i, j;
PLcGrid2 cgrid2;
PLFLT rmax, xmin, xmax, x0, ymin, ymax, y0, zmin, zmax;
PLFLT peps, xpmin, xpmax, ypmin, ypmax;
PLFLT eps, q1, d1, q1i, d1i, q2, d2, q2i, d2i;
PLFLT div1, div1i, div2, div2i;
PLFLT **z;
PLINT nlevelneg, nlevelpos;
PLFLT dz, clevel2, clevelneg[PNLEVEL], clevelpos[PNLEVEL];
PLINT ncollin, ncolbox, ncollab;
PLFLT px[PPERIMETERPTS], py[PPERIMETERPTS];
PLFLT t, r, theta;
//create data to be contoured.
plAlloc2dGrid( &cgrid2.xg, PRPTS, PTHETAPTS );
plAlloc2dGrid( &cgrid2.yg, PRPTS, PTHETAPTS );
plAlloc2dGrid( &z, PRPTS, PTHETAPTS );
cgrid2.nx = PRPTS;
cgrid2.ny = PTHETAPTS;
for ( i = 0; i < PRPTS; i++ )
{
r = 0.5 + (PLFLT) i;
for ( j = 0; j < PTHETAPTS; j++ )
{
theta = ( 2. * M_PI / (PLFLT) ( PTHETAPTS - 1 ) ) * ( 0.5 + (PLFLT) j );
cgrid2.xg[i][j] = r * cos( theta );
cgrid2.yg[i][j] = r * sin( theta );
}
}
rmax = r;
f2mnmx( cgrid2.xg, PRPTS, PTHETAPTS, &xmin, &xmax );
f2mnmx( cgrid2.yg, PRPTS, PTHETAPTS, &ymin, &ymax );
x0 = ( xmin + xmax ) / 2.;
y0 = ( ymin + ymax ) / 2.;
// Expanded limits
peps = 0.05;
xpmin = xmin - fabs( xmin ) * peps;
xpmax = xmax + fabs( xmax ) * peps;
ypmin = ymin - fabs( ymin ) * peps;
ypmax = ymax + fabs( ymax ) * peps;
// Potential inside a conducting cylinder (or sphere) by method of images.
// Charge 1 is placed at (d1, d1), with image charge at (d2, d2).
// Charge 2 is placed at (d1, -d1), with image charge at (d2, -d2).
// Also put in smoothing term at small distances.
//
eps = 2.;
q1 = 1.;
d1 = rmax / 4.;
q1i = -q1 * rmax / d1;
d1i = pow( rmax, 2. ) / d1;
q2 = -1.;
d2 = rmax / 4.;
q2i = -q2 * rmax / d2;
d2i = pow( rmax, 2. ) / d2;
for ( i = 0; i < PRPTS; i++ )
{
for ( j = 0; j < PTHETAPTS; j++ )
{
div1 = sqrt( pow( cgrid2.xg[i][j] - d1, 2. ) + pow( cgrid2.yg[i][j] - d1, 2. ) + pow( eps, 2. ) );
div1i = sqrt( pow( cgrid2.xg[i][j] - d1i, 2. ) + pow( cgrid2.yg[i][j] - d1i, 2. ) + pow( eps, 2. ) );
div2 = sqrt( pow( cgrid2.xg[i][j] - d2, 2. ) + pow( cgrid2.yg[i][j] + d2, 2. ) + pow( eps, 2. ) );
div2i = sqrt( pow( cgrid2.xg[i][j] - d2i, 2. ) + pow( cgrid2.yg[i][j] + d2i, 2. ) + pow( eps, 2. ) );
z[i][j] = q1 / div1 + q1i / div1i + q2 / div2 + q2i / div2i;
}
}
f2mnmx( z, PRPTS, PTHETAPTS, &zmin, &zmax );
// printf("%.15g %.15g %.15g %.15g %.15g %.15g %.15g %.15g \n",
// q1, d1, q1i, d1i, q2, d2, q2i, d2i);
// printf("%.15g %.15g %.15g %.15g %.15g %.15g \n",
// xmin, xmax, ymin, ymax, zmin, zmax);
// Positive and negative contour levels.
dz = ( zmax - zmin ) / (PLFLT) PNLEVEL;
nlevelneg = 0;
nlevelpos = 0;
for ( i = 0; i < PNLEVEL; i++ )
{
clevel2 = zmin + ( (PLFLT) i + 0.5 ) * dz;
if ( clevel2 <= 0. )
clevelneg[nlevelneg++] = clevel2;
else
clevelpos[nlevelpos++] = clevel2;
}
// Colours!
ncollin = 11;
ncolbox = 1;
ncollab = 2;
// Finally start plotting this page!
pladv( 0 );
plcol0( ncolbox );
plvpas( 0.1, 0.9, 0.1, 0.9, 1.0 );
plwind( xpmin, xpmax, ypmin, ypmax );
plbox( "", 0., 0, "", 0., 0 );
plcol0( ncollin );
if ( nlevelneg > 0 )
{
// Negative contours
pllsty( 2 );
plcont( (PLFLT_MATRIX) z, PRPTS, PTHETAPTS, 1, PRPTS, 1, PTHETAPTS,
clevelneg, nlevelneg, pltr2, (void *) &cgrid2 );
}
if ( nlevelpos > 0 )
{
// Positive contours
pllsty( 1 );
plcont( (PLFLT_MATRIX) z, PRPTS, PTHETAPTS, 1, PRPTS, 1, PTHETAPTS,
clevelpos, nlevelpos, pltr2, (void *) &cgrid2 );
}
// Draw outer boundary
for ( i = 0; i < PPERIMETERPTS; i++ )
{
t = ( 2. * M_PI / ( PPERIMETERPTS - 1 ) ) * (PLFLT) i;
px[i] = x0 + rmax * cos( t );
py[i] = y0 + rmax * sin( t );
}
plcol0( ncolbox );
plline( PPERIMETERPTS, px, py );
plcol0( ncollab );
pllab( "", "", "Shielded potential of charges in a conducting sphere" );
plFree2dGrid( z, PRPTS, PTHETAPTS );
plFree2dGrid( cgrid2.xg, PRPTS, PTHETAPTS );
plFree2dGrid( cgrid2.yg, PRPTS, PTHETAPTS );
}
//--------------------------------------------------------------------------
// main
//
// Does several contour plots using different coordinate mappings.
//--------------------------------------------------------------------------
int
main( int argc, char *argv[] )
{
int i, j;
PLFLT xx, yy, argx, argy, distort;
static PLINT mark = 1500, space = 1500;
PLFLT **z, **w;
PLFLT xg1[XPTS], yg1[YPTS];
PLcGrid cgrid1;
PLcGrid2 cgrid2;
// Parse and process command line arguments
(void) plparseopts( &argc, argv, PL_PARSE_FULL );
// Initialize plplot
plinit();
// Set up function arrays
plAlloc2dGrid( &z, XPTS, YPTS );
plAlloc2dGrid( &w, XPTS, YPTS );
for ( i = 0; i < XPTS; i++ )
{
xx = (PLFLT) ( i - ( XPTS / 2 ) ) / (PLFLT) ( XPTS / 2 );
for ( j = 0; j < YPTS; j++ )
{
yy = (PLFLT) ( j - ( YPTS / 2 ) ) / (PLFLT) ( YPTS / 2 ) - 1.0;
z[i][j] = xx * xx - yy * yy;
w[i][j] = 2 * xx * yy;
}
}
// Set up grids
cgrid1.xg = xg1;
cgrid1.yg = yg1;
cgrid1.nx = XPTS;
cgrid1.ny = YPTS;
plAlloc2dGrid( &cgrid2.xg, XPTS, YPTS );
plAlloc2dGrid( &cgrid2.yg, XPTS, YPTS );
cgrid2.nx = XPTS;
cgrid2.ny = YPTS;
for ( i = 0; i < XPTS; i++ )
{
for ( j = 0; j < YPTS; j++ )
{
mypltr( (PLFLT) i, (PLFLT) j, &xx, &yy, NULL );
argx = xx * M_PI / 2;
argy = yy * M_PI / 2;
distort = 0.4;
cgrid1.xg[i] = xx + distort * cos( argx );
cgrid1.yg[j] = yy - distort * cos( argy );
cgrid2.xg[i][j] = xx + distort * cos( argx ) * cos( argy );
cgrid2.yg[i][j] = yy - distort * cos( argx ) * cos( argy );
}
}
// Plot using identity transform
//
// plenv(-1.0, 1.0, -1.0, 1.0, 0, 0);
// plcol0(2);
// plcont(z, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11, mypltr, NULL);
// plstyl(1, &mark, &space);
// plcol0(3);
// plcont(w, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11, mypltr, NULL);
// plstyl(0, &mark, &space);
// plcol0(1);
// pllab("X Coordinate", "Y Coordinate", "Streamlines of flow");
//
pl_setcontlabelformat( 4, 3 );
pl_setcontlabelparam( 0.006, 0.3, 0.1, 1 );
plenv( -1.0, 1.0, -1.0, 1.0, 0, 0 );
plcol0( 2 );
plcont( (PLFLT_MATRIX) z, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11, mypltr, NULL );
plstyl( 1, &mark, &space );
plcol0( 3 );
plcont( (PLFLT_MATRIX) w, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11, mypltr, NULL );
plstyl( 0, &mark, &space );
plcol0( 1 );
pllab( "X Coordinate", "Y Coordinate", "Streamlines of flow" );
pl_setcontlabelparam( 0.006, 0.3, 0.1, 0 );
// Plot using 1d coordinate transform
plenv( -1.0, 1.0, -1.0, 1.0, 0, 0 );
plcol0( 2 );
plcont( (PLFLT_MATRIX) z, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
pltr1, (void *) &cgrid1 );
plstyl( 1, &mark, &space );
plcol0( 3 );
plcont( (PLFLT_MATRIX) w, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
pltr1, (void *) &cgrid1 );
plstyl( 0, &mark, &space );
plcol0( 1 );
pllab( "X Coordinate", "Y Coordinate", "Streamlines of flow" );
//
// pl_setcontlabelparam(0.006, 0.3, 0.1, 1);
// plenv(-1.0, 1.0, -1.0, 1.0, 0, 0);
// plcol0(2);
// plcont((const PLFLT **) z, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
// pltr1, (void *) &cgrid1);
//
// plstyl(1, &mark, &space);
// plcol0(3);
// plcont((const PLFLT **) w, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
// pltr1, (void *) &cgrid1);
// plstyl(0, &mark, &space);
// plcol0(1);
// pllab("X Coordinate", "Y Coordinate", "Streamlines of flow");
// pl_setcontlabelparam(0.006, 0.3, 0.1, 0);
//
// Plot using 2d coordinate transform
plenv( -1.0, 1.0, -1.0, 1.0, 0, 0 );
plcol0( 2 );
plcont( (PLFLT_MATRIX) z, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
pltr2, (void *) &cgrid2 );
plstyl( 1, &mark, &space );
plcol0( 3 );
plcont( (PLFLT_MATRIX) w, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
pltr2, (void *) &cgrid2 );
plstyl( 0, &mark, &space );
plcol0( 1 );
pllab( "X Coordinate", "Y Coordinate", "Streamlines of flow" );
//
// pl_setcontlabelparam(0.006, 0.3, 0.1, 1);
// plenv(-1.0, 1.0, -1.0, 1.0, 0, 0);
// plcol0(2);
// plcont((const PLFLT **) z, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
// pltr2, (void *) &cgrid2);
//
// plstyl(1, &mark, &space);
// plcol0(3);
// plcont((const PLFLT **) w, XPTS, YPTS, 1, XPTS, 1, YPTS, clevel, 11,
// pltr2, (void *) &cgrid2);
// plstyl(0, &mark, &space);
// plcol0(1);
// pllab("X Coordinate", "Y Coordinate", "Streamlines of flow");
//
pl_setcontlabelparam( 0.006, 0.3, 0.1, 0 );
polar();
//
// pl_setcontlabelparam(0.006, 0.3, 0.1, 1);
// polar();
//
pl_setcontlabelparam( 0.006, 0.3, 0.1, 0 );
potential();
//
// pl_setcontlabelparam(0.006, 0.3, 0.1, 1);
// potential();
//
// Clean up
plFree2dGrid( z, XPTS, YPTS );
plFree2dGrid( w, XPTS, YPTS );
plFree2dGrid( cgrid2.xg, XPTS, YPTS );
plFree2dGrid( cgrid2.yg, XPTS, YPTS );
plend();
exit( 0 );
}