[Plplot-cvs] plplot/examples/c++ x22.cc,1.6,1.7

[Andrew R. <and...@us...>]

Update of /cvsroot/plplot/plplot/examples/c++
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv7265/examples/c++

Modified Files:
	x22.cc 
Log Message:

Add plvect and plsvect to the common API.

Add java, python and tcl bindings and examples for plvect and plsvect. 

Modify example 22 and make C, C++, fortran, java, python and tcl versions 
consistent. C, C++, fortran and tcl versions of example 22 now produce 
identical results. There appear to be some rounding errors with java and
python.


Index: x22.cc
===================================================================
RCS file: /cvsroot/plplot/plplot/examples/c++/x22.cc,v
retrieving revision 1.6
retrieving revision 1.7
diff -u -d -r1.6 -r1.7
--- x22.cc	3 Mar 2004 17:41:16 -0000	1.6
+++ x22.cc	21 May 2004 15:09:25 -0000	1.7
@@ -39,18 +39,222 @@
 class x22 {
 
 public:
-  x22(int, char **);
+    x22(int, char **);
 
 private:
-  plstream *pls;
+    void circulation();
+    void constriction();
+    void potential();
+    void f2mnmx(PLFLT **f, PLINT nx, PLINT ny, PLFLT *fmin, PLFLT *fmax);
+
+    PLFLT MIN(PLFLT x, PLFLT y) { return (x<y?x:y);};
+    PLFLT MAX(PLFLT x, PLFLT y) { return (x>y?x:y);};
+  
+    plstream *pls;
+  
+    PLFLT **u, **v;
+    PLcGrid2 cgrid2;
+    int nx, ny;
 
 };
 
+// Vector plot of the circulation about the origin
+void
+x22::circulation() {
+    int i,j;
+    PLFLT dx, dy, x, y;
+    PLFLT xmin, xmax, ymin, ymax;
+
+    dx = 1.0;
+    dy = 1.0;
+
+    xmin = -nx/2*dx;
+    xmax = nx/2*dx;
+    ymin = -ny/2*dy;
+    ymax = ny/2*dy;
+
+
+    // Create data - cirulation around the origin.
+    for (i = 0; i<nx; i++) {
+	for (j = 0; j<ny; j++) {
+	    x = (i-nx/2+0.5)*dx;
+	    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
+    pls->env(xmin, xmax, ymin, ymax, 0, 0);
+    pls->lab("(x)", "(y)", "#frPLplot Example 22 - circulation");
+    pls->col0(2);
+    pls->vect(u,v,nx,ny,0.0,pltr2,(void *)&cgrid2);
+    pls->col0(1);
+
+}
+
+// Vector plot of flow through a constricted pipe
+void
+x22::constriction() {
+    int i,j;
+    PLFLT dx, dy, x, y;
+    PLFLT xmin, xmax, ymin, ymax;
+    PLFLT Q, b, dbdx;
+
+    dx = 1.0;
+    dy = 1.0;
+
+    xmin = -nx/2*dx;
+    xmax = nx/2*dx;
+    ymin = -ny/2*dy;
+    ymax = ny/2*dy;
+
+    Q = 2.0;
+    for (i = 0; i<nx; i++) {
+	for (j = 0; j<ny; j++) {
+	    x = (i-nx/2+0.5)*dx;
+	    y = (j-ny/2+0.5)*dy;
+	    cgrid2.xg[i][j] = x;
+	    cgrid2.yg[i][j] = y;
+	    b = ymax/4.0*(3-cos(M_PI*x/xmax));
+	    if (fabs(y) < b) {
+		dbdx = ymax/4.0*sin(M_PI*x/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;
+	    }
+	}
+    }
+
+    pls->env(xmin, xmax, ymin, ymax, 0, 0);
+    pls->lab("(x)", "(y)", "#frPLplot Example 22 - constriction");
+    pls->col0(2);
+    pls->vect(u,v,nx,ny,-0.5,pltr2,(void *)&cgrid2);
+    pls->col0(1);
+
+}
+
+// Vector plot of the gradient of a shielded potential (see example 9)
+void
+x22::potential() {
+	
+    const int nper = 100;
+    const int nlevel = 10;
+
+    int i,j, nr, ntheta;
+    PLFLT eps, q1, d1, q1i, d1i, q2, d2, q2i, d2i;
+    PLFLT div1, div1i, div2, div2i;
+    PLFLT **z, r, theta, x, y, dz;
+    PLFLT xmin, xmax, ymin, ymax, rmax, zmax, zmin;
+    PLFLT px[nper], py[nper], clevel[nlevel];
+
+    nr = nx;
+    ntheta = ny;
+  
+    // Create data to be plotted
+    pls->Alloc2dGrid(&z,nr,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.
+
+    rmax = (double) nr;
+
+    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 < nr; i++) {
+	r = 0.5 + (double) i;
+	for (j = 0; j < ntheta; j++) {
+	    theta = 2.*M_PI/(ntheta-1)*(0.5+(double)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.) + pow(y-d1, 2.) + pow(eps, 2.));
+	    div1i = sqrt(pow(x-d1i, 2.) + pow(y-d1i, 2.) + pow(eps, 2.));
+	    div2 = sqrt(pow(x-d2, 2.) + pow(y+d2, 2.) + pow(eps, 2.));
+	    div2i = sqrt(pow(x-d2i, 2.) + pow(y+d2i, 2.) + pow(eps, 2.));
+	    z[i][j] = q1/div1 + q1i/div1i + q2/div2 + q2i/div2i;
+	    u[i][j] = -q1*(x-d1)/pow(div1,3.) - q1i*(x-d1i)/pow(div1i,3.0) 
+		- q2*(x-d2)/pow(div2,3.) - q2i*(x-d2i)/pow(div2i,3.);
+	    v[i][j] = -q1*(y-d1)/pow(div1,3.) - q1i*(y-d1i)/pow(div1i,3.0) 
+		- q2*(y+d2)/pow(div2,3.) - q2i*(y+d2i)/pow(div2i,3.);
+	}
+    }
+
+    f2mnmx(cgrid2.xg, nr, ntheta, &xmin, &xmax);
+    f2mnmx(cgrid2.yg, nr, ntheta, &ymin, &ymax);
+    f2mnmx(z, nr, ntheta, &zmin, &zmax);
+
+    pls->env(xmin, xmax, ymin, ymax, 0, 0);
+    pls->lab("(x)", "(y)", "#frPLplot Example 22 - potential gradient vector plot");
+    // Plot contours of the potential
+    dz = (zmax-zmin)/(double) nlevel;
+    for (i = 0; i < nlevel; i++) {
+	clevel[i] = zmin + ((double) i + 0.5)*dz;
+    }
+    pls->col0(3);
+    pls->lsty(2);
+    pls->cont(z,nr,ntheta,1,nr,1,ntheta,clevel,nlevel,pltr2,(void *) &cgrid2);
+    pls->lsty(1);
+    pls->col0(1);
+    
+    // Plot the vectors of the gradient of the potential
+    pls->col0(2);
+    pls->vect(u,v,nr,ntheta,25.0,pltr2,(void *)&cgrid2);
+    pls->col0(1);
+
+    // Plot the perimeter of the cylinder
+    for (i=0;i<nper;i++) {
+	theta = (2.*M_PI/(nper-1))*(double)i;
+	px[i] = rmax*cos(theta);
+	py[i] = rmax*sin(theta);
+    }
+    pls->line(nper,px,py);
+    
+    pls->Free2dGrid(z,nr,ntheta);
+
+}
+
+void
+x22::f2mnmx(PLFLT **f, PLINT nx, PLINT ny, PLFLT *fmin, PLFLT *fmax)
+{
+    int i, j;
+
+    *fmax = f[0][0];
+    *fmin = *fmax;
+
+    for (i = 0; i < nx; i++) {
+	for (j = 0; j < ny; j++) {
+	    *fmax = MAX(*fmax, f[i][j]);
+	    *fmin = MIN(*fmin, f[i][j]);
+	}
+    }
+}
+
 
 x22::x22( int argc, char ** argv ) {
 
-    PLFLT **u, **v;
-    PLcGrid2 cgrid2;
+    PLINT narr, fill;
 
     // Set of points making a polygon to use as the arrow
     PLFLT arrow_x[6] = {-0.5, 0.5, 0.3, 0.5, 0.3, 0.5};
@@ -58,10 +262,6 @@
     PLFLT arrow2_x[6] = {-0.5, 0.3, 0.3, 0.5, 0.3, 0.3};
     PLFLT arrow2_y[6] = {0.0, 0.0,   0.2, 0.0, -0.2, 0.0};
 
-    int i,j, nx, ny, npts;
-    PLFLT dx, dy, dr, r, theta;
-    PLFLT xmin, xmax, ymin, ymax;
-    PLINT narr, fill;
 
     // Create new plstream
     pls = new plstream();
@@ -74,12 +274,8 @@
 
     pls->init();
 
-    dx = 1.0;
-    dy = 1.0;
-
-    nx = 10;
-    ny = 10;
-    npts = nx*ny;
+    nx = 20;
+    ny = 20;
 
     // Allocate arrays
     pls->Alloc2dGrid(&cgrid2.xg,nx,ny);
@@ -90,27 +286,7 @@
     cgrid2.nx = nx;
     cgrid2.ny = ny;
 
-    xmin = -nx/2*dx;
-    xmax = nx/2*dx;
-    ymin = -ny/2*dy;
-    ymax = ny/2*dy;
-
-    // Create data - cirulation around the origin.
-    for (i = 0; i<nx; i++) {
-	for (j = 0; j<ny; j++) {
-	    cgrid2.xg[i][j] = (i-nx/2+0.5)*dx;
-	    cgrid2.yg[i][j] = (j-ny/2+0.5)*dy;
-	    u[i][j] = cgrid2.yg[i][j];
-	    v[i][j] = -cgrid2.xg[i][j];
-	}
-    }
-
-    // Plot vectors with default arrows
-    pls->env(xmin, xmax, ymin, ymax, 0, 0);
-    pls->lab("(x)", "(y)", "#frPLplot Example 22 - vector plot");
-    pls->col0(2);
-    plvect(u,v,nx,ny,0.0,pltr2,(void *)&cgrid2);
-    pls->col0(1);
+    circulation();
 
     narr = 6;
     fill = 0;
@@ -118,46 +294,15 @@
     // Set arrow style using arrow_x and arrow_y then 
     // plot using these arrows.
     pls->svect(arrow_x, arrow_y, narr, fill);
-    pls->env(xmin, xmax, ymin, ymax, 0, 0);
-    pls->lab("(x)", "(y)", "#frPLplot Example 22 - user defined arrow");
-    pls->col0(2);
-    plvect(u,v,nx,ny,-0.5,pltr2,(void *)&cgrid2);
-    pls->col0(1);
-
-    fill = 1;
+    constriction();
 
     // Set arrow style using arrow2_x and arrow2_y then 
     // plot using these filled arrows.
+    fill = 1;
     pls->svect(arrow2_x, arrow2_y, narr, fill);
-    pls->env(xmin, xmax, ymin, ymax, 0, 0);
-    pls->lab("(x)", "(y)", "#frPLplot Example 22 - filled arrow");
-    pls->col0(2);
-    plvect(u,v,nx,ny,0.3,pltr2,(void *)&cgrid2);
-    pls->col0(1);
-
-    dr = 0.5;
-
-    for (i = 0; i<nx; i++) {
-        r = i*dr;
-	for (j = 0; j<ny; j++) {
-	    theta = 2.*M_PI/(ny-1)*(double)j;
-	    cgrid2.xg[i][j] = r*cos(theta);
-	    cgrid2.yg[i][j] = r*sin(theta);
-	    u[i][j] = cgrid2.yg[i][j];
-	    v[i][j] = -cgrid2.xg[i][j];
-	}
-    }	
-
-    xmin = -nx*dr;
-    xmax = nx*dr;
-    ymin = -nx*dr;
-    ymax = nx*dr;
+    constriction();
 
-    pls->env(xmin, xmax, ymin, ymax, 0, 0);
-    pls->lab("(x)", "(y)", "#frPLplot Example 22 - polar vector plot");
-    pls->col0(2);
-    pls->vect(u,v,nx,ny,0.5,pltr2,(void *)&cgrid2);
-    pls->col0(1);
+    potential();
 
     pls->Free2dGrid(cgrid2.xg,nx,ny);
     pls->Free2dGrid(cgrid2.yg,nx,ny);
@@ -169,8 +314,8 @@
 }
 
 int main( int argc, char ** argv ) {
-  x22 *x = new x22( argc, argv );
-  delete x;
+    x22 *x = new x22( argc, argv );
+    delete x;
 
 }