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//
// Simple vector plot example
// Copyright (C) 2009 Werner Smekal
//
//
// 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
//
//
import std.math;
import std.string;
import plplot;
//
// Global transform function for a constriction using data passed in
// This is the same transformation used in constriction.
//
extern ( C ) {
void
transform( PLFLT x, PLFLT y, PLFLT *xt, PLFLT *yt, PLPointer data )
{
PLFLT *xmax = cast(PLFLT *) data;
*xt = x;
*yt = y / 4.0 * ( 3 - cos( PI * x / *xmax ) );
}
}
//--------------------------------------------------------------------------
// main
//
// Generates several simple vector plots.
//--------------------------------------------------------------------------
class plot {
//
// Vector plot of the circulation about the origin
//
void circulation()
{
const int nx = 20;
const int ny = 20;
PLFLT dx = 1.0;
PLFLT dy = 1.0;
PLFLT xmin = -nx / 2 * dx;
PLFLT xmax = nx / 2 * dx;
PLFLT ymin = -ny / 2 * dy;
PLFLT ymax = ny / 2 * dy;
PLcGrid2 cgrid2;
cgrid2.xg = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
cgrid2.xg[i] = new PLFLT[ny];
cgrid2.yg = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
cgrid2.yg[i] = new PLFLT[ny];
PLFLT[][] u = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
u[i] = new PLFLT[ny];
PLFLT[][] v = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
v[i] = new PLFLT[ny];
// Create data - circulation around the origin.
PLFLT x, y;
for ( int i = 0; i < nx; i++ )
{
x = ( i - nx / 2 + 0.5 ) * dx;
for ( int j = 0; j < ny; j++ )
{
y = ( j - ny / 2 + 0.5 ) * dy;
cgrid2.xg[i][j] = x;
cgrid2.yg[i][j] = y;
u[i][j] = y;
v[i][j] = -x;
}
}
// Plot vectors with default arrows
plenv( xmin, xmax, ymin, ymax, 0, 0 );
pllab( "(x)", "(y)", "#frPLplot Example 22 - circulation" );
plcol0( 2 );
plvect( u, v, 0.0, cgrid2 );
plcol0( 1 );
}
//
// Vector plot of flow through a constricted pipe
//
void
constriction( int astyle )
{
const int nx = 20;
const int ny = 20;
string title;
PLFLT dx = 1.0;
PLFLT dy = 1.0;
PLFLT xmin = -nx / 2 * dx;
PLFLT xmax = nx / 2 * dx;
PLFLT ymin = -ny / 2 * dy;
PLFLT ymax = ny / 2 * dy;
PLcGrid2 cgrid2;
cgrid2.xg = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
cgrid2.xg[i] = new PLFLT[ny];
cgrid2.yg = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
cgrid2.yg[i] = new PLFLT[ny];
PLFLT[][] u = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
u[i] = new PLFLT[ny];
PLFLT[][] v = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
v[i] = new PLFLT[ny];
PLFLT Q = 2.0;
PLFLT x, y, b, dbdx;
for ( int i = 0; i < nx; i++ )
{
x = ( i - nx / 2 + 0.5 ) * dx;
for ( int j = 0; j < ny; j++ )
{
y = ( j - ny / 2 + 0.5 ) * dy;
cgrid2.xg[i][j] = x;
cgrid2.yg[i][j] = y;
b = ymax / 4.0 * ( 3 - cos( PI * x / xmax ) );
if ( fabs( y ) < b )
{
dbdx = ymax / 4.0 * sin( PI * x / xmax ) * PI / xmax * y / b;
u[i][j] = Q * ymax / b;
v[i][j] = dbdx * u[i][j];
}
else
{
u[i][j] = 0.0;
v[i][j] = 0.0;
}
}
}
plenv( xmin, xmax, ymin, ymax, 0, 0 );
title = format( "#frPLplot Example 22 - constriction (arrow style %d)", astyle );
pllab( "(x)", "(y)", title );
plcol0( 2 );
plvect( u, v, -1.0, cgrid2 );
plcol0( 1 );
}
//
// Vector plot of flow through a constricted pipe
// with a coordinate transform
//
void
constriction2()
{
const int nx = 20;
const int ny = 20;
const int nc = 11;
const int nseg = 20;
PLFLT [] clev = new PLFLT[nc];
PLFLT dx = 1.0;
PLFLT dy = 1.0;
PLFLT xmin = -nx / 2 * dx;
PLFLT xmax = nx / 2 * dx;
PLFLT ymin = -ny / 2 * dy;
PLFLT ymax = ny / 2 * dy;
plstransform( &transform, cast(PLPointer) &xmax );
PLcGrid2 cgrid2;
cgrid2.xg = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
cgrid2.xg[i] = new PLFLT[ny];
cgrid2.yg = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
cgrid2.yg[i] = new PLFLT[ny];
PLFLT[][] u = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
u[i] = new PLFLT[ny];
PLFLT[][] v = new PLFLT[][nx];
for ( int i = 0; i < nx; i++ )
v[i] = new PLFLT[ny];
PLFLT Q = 2.0;
PLFLT x, y, b, dbdx;
for ( int i = 0; i < nx; i++ )
{
x = ( i - nx / 2 + 0.5 ) * dx;
for ( int j = 0; j < ny; j++ )
{
y = ( j - ny / 2 + 0.5 ) * dy;
cgrid2.xg[i][j] = x;
cgrid2.yg[i][j] = y;
b = ymax / 4.0 * ( 3 - cos( PI * x / xmax ) );
u[i][j] = Q * ymax / b;
v[i][j] = 0.0;
}
}
for ( int i = 0; i < nc; i++ )
{
clev[i] = Q + i * Q / ( nc - 1 );
}
plenv( xmin, xmax, ymin, ymax, 0, 0 );
pllab( "(x)", "(y)", "#frPLplot Example 22 - constriction with plstransform" );
plcol0( 2 );
plshades( u, null, xmin + dx / 2, xmax - dx / 2,
ymin + dy / 2, ymax - dy / 2,
clev, 0.0, 1, 1.0, 0 );
plvect( u, v, -1.0, cgrid2 );
// Plot edges using plpath (which accounts for coordinate transformation) rather than plline
plpath( nseg, xmin, ymax, xmax, ymax );
plpath( nseg, xmin, ymin, xmax, ymin );
plcol0( 1 );
plstransform( null, null );
}
//--------------------------------------------------------------------------
// f2mnmx
//
// Returns min & max of input 2d array.
//--------------------------------------------------------------------------
void f2mnmx( PLFLT[][] f, out PLFLT fmn, out PLFLT fmx )
{
fmx = f[0][0];
fmn = fmx;
for ( int i = 0; i < f.length; i++ )
{
for ( int j = 0; j < f[i].length; j++ )
{
fmx = fmax( fmx, f[i][j] );
fmn = fmin( fmn, f[i][j] );
}
}
}
//
// Vector plot of the gradient of a shielded potential (see example 9)
//
void potential()
{
const int nper = 100;
const int nlevel = 10;
const int nr = 20;
const int ntheta = 20;
PLcGrid2 cgrid2;
cgrid2.xg = new PLFLT[][nr];
for ( int i = 0; i < nr; i++ )
cgrid2.xg[i] = new PLFLT[ntheta];
cgrid2.yg = new PLFLT[][nr];
for ( int i = 0; i < nr; i++ )
cgrid2.yg[i] = new PLFLT[ntheta];
PLFLT[][] u = new PLFLT[][nr];
for ( int i = 0; i < nr; i++ )
u[i] = new PLFLT[ntheta];
PLFLT[][] v = new PLFLT[][nr];
for ( int i = 0; i < nr; i++ )
v[i] = new PLFLT[ntheta];
PLFLT[][] z = new PLFLT[][nr];
for ( int i = 0; i < nr; i++ )
z[i] = new PLFLT[ntheta];
// 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.
//
PLFLT rmax = nr;
PLFLT eps = 2.0;
PLFLT q1 = 1.0;
PLFLT d1 = rmax / 4.0;
PLFLT q1i = -q1 * rmax / d1;
PLFLT d1i = pow( rmax, 2.0 ) / d1;
PLFLT q2 = -1.0;
PLFLT d2 = rmax / 4.0;
PLFLT q2i = -q2 * rmax / d2;
PLFLT d2i = pow( rmax, 2.0 ) / d2;
PLFLT r, theta, x, y;
PLFLT div1, div1i, div2, div2i;
for ( int i = 0; i < nr; i++ )
{
r = 0.5 + i;
for ( int j = 0; j < ntheta; j++ )
{
theta = 2.0 * PI / ( ntheta - 1 ) * ( 0.5 + j );
x = r * cos( theta );
y = r * sin( theta );
cgrid2.xg[i][j] = x;
cgrid2.yg[i][j] = y;
div1 = sqrt( pow( x - d1, 2.0 ) + pow( y - d1, 2.0 ) + pow( eps, 2.0 ) );
div1i = sqrt( pow( x - d1i, 2.0 ) + pow( y - d1i, 2.0 ) + pow( eps, 2.0 ) );
div2 = sqrt( pow( x - d2, 2.0 ) + pow( y + d2, 2.0 ) + pow( eps, 2.0 ) );
div2i = sqrt( pow( x - d2i, 2.0 ) + pow( y + d2i, 2.0 ) + pow( eps, 2.0 ) );
z[i][j] = q1 / div1 + q1i / div1i + q2 / div2 + q2i / div2i;
u[i][j] = -q1 * ( x - d1 ) / pow( div1, 3.0 ) - q1i * ( x - d1i ) / pow( div1i, 3.0 )
- q2 * ( x - d2 ) / pow( div2, 3.0 ) - q2i * ( x - d2i ) / pow( div2i, 3.0 );
v[i][j] = -q1 * ( y - d1 ) / pow( div1, 3.0 ) - q1i * ( y - d1i ) / pow( div1i, 3.0 )
- q2 * ( y + d2 ) / pow( div2, 3.0 ) - q2i * ( y + d2i ) / pow( div2i, 3.0 );
}
}
PLFLT xmin, xmax, ymin, ymax, zmin, zmax;
f2mnmx( cgrid2.xg, xmin, xmax );
f2mnmx( cgrid2.yg, ymin, ymax );
f2mnmx( z, zmin, zmax );
plenv( xmin, xmax, ymin, ymax, 0, 0 );
pllab( "(x)", "(y)", "#frPLplot Example 22 - potential gradient vector plot" );
// Plot contours of the potential
PLFLT dz = ( zmax - zmin ) / nlevel;
PLFLT[] clevel = new PLFLT[nlevel];
for ( int i = 0; i < nlevel; i++ )
clevel[i] = zmin + ( i + 0.5 ) * dz;
plcol0( 3 );
pllsty( 2 );
plcont( z, 1, nr, 1, ntheta, clevel, cgrid2 );
pllsty( 1 );
plcol0( 1 );
// Plot the vectors of the gradient of the potential
plcol0( 2 );
plvect( u, v, 25.0, cgrid2 );
plcol0( 1 );
// Plot the perimeter of the cylinder
PLFLT[] px = new PLFLT[nper];
PLFLT[] py = new PLFLT[nper];
for ( int i = 0; i < nper; i++ )
{
theta = ( 2.0 * PI / ( nper - 1 ) ) * i;
px[i] = rmax * cos( theta );
py[i] = rmax * sin( theta );
}
plline( px, py );
}
}
int main( char[][] args )
{
// Parse and process command line arguments
plparseopts( args, PL_PARSE_FULL );
// Initialize plplot
plinit();
plot myPlot = new plot;
myPlot.circulation();
PLINT fill = 0;
// Pairs of points making the line segments used to plot the user defined arrow
PLFLT[] arrow_x = [ -0.5, 0.5, 0.3, 0.5, 0.3, 0.5 ];
PLFLT[] arrow_y = [ 0.0, 0.0, 0.2, 0.0, -0.2, 0.0 ];
// Set arrow style using arrow_x and arrow_y then
// plot using these arrows.
plsvect( arrow_x, arrow_y, fill );
myPlot.constriction( 1 );
// Pairs of points making the line segments used to plot the user defined arrow
PLFLT[] arrow2_x = [ -0.5, 0.3, 0.3, 0.5, 0.3, 0.3 ];
PLFLT[] arrow2_y = [ 0.0, 0.0, 0.2, 0.0, -0.2, 0.0 ];
// Set arrow style using arrow2_x and arrow2_y then
// plot using these filled arrows.
fill = 1;
plsvect( arrow2_x, arrow2_y, fill );
myPlot.constriction( 2 );
myPlot.constriction2();
plsvect( null, null, 0 );
myPlot.potential();
plend();
return 0;
}
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