/usr/share/doc/libplplot12/examples/ada/x09a.adb is in libplplot-ada1-dev 5.10.0+dfsg2-0.1ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 | -- $Id: x09a.adb 11680 2011-03-27 17:57:51Z airwin $
-- Contour plot demo.
-- Copyright (C) 2008 Jerry Bauck
-- 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
with
System,
Ada.Numerics,
Ada.Numerics.Long_Elementary_Functions,
PLplot_Traditional,
PLplot_Auxiliary;
use
Ada.Numerics,
Ada.Numerics.Long_Elementary_Functions,
System,
PLplot_Traditional,
PLplot_Auxiliary;
--------------------------------------------------------------------------
-- Does several contour plots using different coordinate mappings.
--------------------------------------------------------------------------
procedure x09a is
XPTS : Integer := 35; -- Number of data points in x
YPTS : Integer := 46; -- Number of data points in y
-- polar plot data
PERIMETERPTS : Integer := 100;
RPTS : Integer := 40;
THETAPTS : Integer := 40;
-- potential plot data
PPERIMETERPTS : Integer := 100;
PRPTS : Integer := 40;
PTHETAPTS : Integer := 64;
PNLEVEL : Integer := 20;
xx, yy, argx, argy, distort : Long_Float;
mark : Integer_Array_1D(1 .. 1);
space : Integer_Array_1D(1 .. 1);
zgdummy : Real_Vector(0 .. 0); -- not used
z, w : Real_Matrix(0 .. XPTS - 1, 0 .. YPTS - 1);
clevel : Real_Vector(0 .. 10) := (-1.0, -0.8, -0.6, -0.4, -0.2, 0.0, 0.2, 0.4, 0.6, 0.8, 1.0);
cgrid1 : aliased Transformation_Data_Type
(x_Last => XPTS - 1,
y_Last => YPTS - 1,
z_Last => 0);
cgrid2 : aliased Transformation_Data_Type_2
(x_Last => XPTS - 1,
y_Last => YPTS - 1);
-- Quick and dirty function for converting from C. Apparently C lacks an
-- exponentiation operator.
-- Don't have a cow over the abs(a) in pow because all calls to pow() in
-- this example have an exponent of 2.0, i.e., squaring. Without the abs()
-- Ada raises an exception. (Why doesn't C?)
function pow(a, b : Long_Float) return Long_Float is
aa : Long_Float;
begin
aa := abs(a);
return aa ** b;
end pow;
procedure mypltr -- This spec is necessary to accommodate pragma Convention().
(x, y : Long_Float;
tx, ty : out Long_Float;
pltr_data : PLpointer);
pragma Convention(Convention => C, Entity => mypltr);
procedure mypltr
(x, y : Long_Float;
tx, ty : out Long_Float;
pltr_data : PLpointer)
is
-- Transformation function
XSPA : Long_Float := 2.0 / Long_Float(XPTS - 1);
YSPA : Long_Float := 2.0 / Long_Float(YPTS - 1);
tr : Real_Vector(0 .. 5) := (XSPA, 0.0, -1.0, 0.0, YSPA, -1.0);
begin -- mypltr
tx := tr(0) * x + tr(1) * y + tr(2);
ty := tr(3) * x + tr(4) * y + tr(5);
end mypltr;
-- Polar contour plot example
procedure polar is
t, r, theta : Long_Float;
px, py : Real_Vector(0 .. PERIMETERPTS - 1);
lev : Real_Vector(0 .. 9);
z : Real_Matrix(0 .. RPTS - 1, 0 .. THETAPTS - 1);
cgrid2 : aliased Transformation_Data_Type_2
(x_Last => RPTS - 1,
y_Last => THETAPTS - 1);
begin -- polar
plenv(-1.0, 1.0, -1.0, 1.0, 0, -2);
plcol0(1);
-- Perimeter
for i in 0 .. PERIMETERPTS - 1 loop
t := (2.0 * pi / Long_Float(PERIMETERPTS - 1)) * Long_Float(i);
px(i) := cos(t);
py(i) := sin(t);
end loop;
plline(px, py);
for i in 0 .. RPTS - 1 loop
r := Long_Float(i) / Long_Float(RPTS - 1);
for j in 0 .. THETAPTS - 1 loop
theta := (2.0 * pi / Long_Float(THETAPTS - 1)) * Long_Float(j);
cgrid2.xg(i, j) := r * cos(theta);
cgrid2.yg(i, j) := r * sin(theta);
z(i, j) := r;
end loop;
end loop;
for i in lev'range loop
lev(i) := 0.05 + 0.10 * Long_Float(i);
end loop;
plcol0(2);
plcont(z, 1, RPTS, 1, THETAPTS, lev, pltr2'access, cgrid2'Address);
plcol0(1);
pllab("", "", "Polar Contour Plot");
end polar;
-- Shielded potential contour plot example
procedure potential is
nlevelneg, nlevelpos : Integer;
ncollin, ncolbox, ncollab : Integer;
rmax, xmin, xmax, x0, ymin, ymax, y0, zmin, zmax : Long_Float;
peps, xpmin, xpmax, ypmin, ypmax : Long_Float;
eps, q1, d1, q1i, d1i, q2, d2, q2i, d2i : Long_Float;
div1, div1i, div2, div2i : Long_Float;
t, r, theta : Long_Float;
dz, clevel : Long_Float;
clevelneg : Real_Vector(0 .. 9); -- Compare with x09c.c which
clevelpos : Real_Vector(0 .. 9); -- over-allocates these arrays.
px, py : Real_Vector(0 .. PPERIMETERPTS - 1);
z : Real_Matrix(0 .. PRPTS - 1, 0 .. PTHETAPTS - 1);
cgrid2 : aliased Transformation_Data_Type_2
(x_Last => PRPTS - 1,
y_Last => PTHETAPTS - 1);
begin -- potential
-- Create data to be contoured.
for i in 0 .. PRPTS - 1 loop
r := 0.5 + Long_Float(i);
for j in 0 .. PTHETAPTS - 1 loop
theta := (2.0 * pi / Long_Float(PTHETAPTS - 1)) * (0.5 + Long_Float(j));
cgrid2.xg(i, j) := r * cos(theta);
cgrid2.yg(i, j) := r * sin(theta);
end loop;
end loop;
rmax := r;
xmin := Matrix_Min(cgrid2.xg);
xmax := Matrix_Max(cgrid2.xg);
ymin := Matrix_Min(cgrid2.yg);
ymax := Matrix_Max(cgrid2.yg);
x0 := (xmin + xmax) / 2.0;
y0 := (ymin + ymax) / 2.0;
-- Expanded limits
peps := 0.05;
xpmin := xmin - abs(xmin) * peps;
xpmax := xmax + abs(xmax) * peps;
ypmin := ymin - abs(ymin) * peps;
ypmax := ymax + abs(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 := 2.0;
q1 := 1.0;
d1 := rmax / 4.0;
q1i := -q1 * rmax / d1;
d1i := rmax * rmax / d1;
q2 := -1.0;
d2 := rmax / 4.0;
q2i := -q2 * rmax / d2;
d2i := rmax * rmax / d2;
for i in 0 .. PRPTS - 1 loop
for j in 0 .. PTHETAPTS - 1 loop
div1 := sqrt(pow(cgrid2.xg(i, j)-d1, 2.0) + pow(cgrid2.yg(i, j)-d1, 2.0) + pow(eps, 2.0));
div1i := sqrt(pow(cgrid2.xg(i, j)-d1i, 2.0) + pow(cgrid2.yg(i, j)-d1i, 2.0) + pow(eps, 2.0));
div2 := sqrt(pow(cgrid2.xg(i, j)-d2, 2.0) + pow(cgrid2.yg(i, j)+d2, 2.0) + pow(eps, 2.0));
div2i := sqrt(pow(cgrid2.xg(i, j)-d2i, 2.0) + pow(cgrid2.yg(i, j)+d2i, 2.0) + pow(eps, 2.0));
z(i, j) := q1/div1 + q1i/div1i + q2/div2 + q2i/div2i;
end loop;
end loop;
zmin := Matrix_Min(z);
zmax := Matrix_Max(z);
-- Positive and negative contour levels.
dz := (zmax - zmin) / Long_Float(PNLEVEL);
nlevelneg := 0;
nlevelpos := 0;
for i in 0 .. PNLEVEL - 1 loop
clevel := zmin + (Long_Float(i) + 0.5) * dz;
if clevel <= 0.0 then
clevelneg(nlevelneg) := clevel;
nlevelneg := nlevelneg + 1;
else
clevelpos(nlevelpos) := clevel;
nlevelpos := nlevelpos + 1;
end if;
end loop;
-- 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, "", 0.0, 0);
plcol0(ncollin);
if nlevelneg >0 then
-- Negative contours
pllsty(2);
plcont(z, 1, PRPTS, 1, PTHETAPTS, clevelneg, pltr2'access, cgrid2'Address);
end if;
if nlevelpos > 0 then
-- Positive contours
pllsty(1);
plcont(z, 1, PRPTS, 1, PTHETAPTS, clevelpos, pltr2'access, cgrid2'Address);
end if;
-- Draw outer boundary
for i in 0 .. PPERIMETERPTS - 1 loop
t := (2.0 * pi / Long_Float(PPERIMETERPTS - 1)) * Long_Float(i);
px(i) := x0 + rmax * cos(t);
py(i) := y0 + rmax * sin(t);
end loop;
plcol0(ncolbox);
plline(px, py);
plcol0(ncollab);
pllab("", "", "Shielded potential of charges in a conducting sphere");
end potential;
begin -- main
-- Parse and process command line arguments
plparseopts(PL_PARSE_FULL);
-- Initialize plplot
plinit;
-- Take care of limitation on singleton positional aggregates.
mark(1) := 1500;
space(1) := 1500;
zgdummy(0) := 0.0;
for i in 0 .. XPTS - 1 loop
xx := Long_Float(i - XPTS / 2) / Long_Float(XPTS / 2);
for j in 0 .. YPTS - 1 loop
yy := Long_Float(j - YPTS / 2) / Long_Float(YPTS / 2) - 1.0;
z(i, j) := xx * xx - yy * yy;
w(i, j) := 2.0 * xx * yy;
end loop;
end loop;
-- Set up grids
cgrid1.zg := zgdummy; -- dummy; not used
for i in 0 .. XPTS - 1 loop
for j in 0 .. YPTS - 1 loop
mypltr(Long_Float(i), Long_Float(j), xx, yy, System.Null_Address); --here
argx := xx * pi / 2.0;
argy := yy * pi / 2.0;
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);
end loop;
end loop;
-- The following use of Unrestricted_Access works but is GNAT-specific.
-- I don't know how else to solve the problem of having a user-specified
-- function that is passed through five or so levels of C as a callback
-- while also not requiring the user to modify the source for plplot_thin.adb
-- which is where the type for the "pltr" subprograms is declared. Even if
-- I move that type declaration into the thick bindings, the problem remains.
pl_setcontlabelformat(4,3);
pl_setcontlabelparam(0.006, 0.3, 0.1, True);
plenv(-1.0, 1.0, -1.0, 1.0, 0, 0);
plcol0(2);
plcont(z, 1, XPTS, 1, YPTS, clevel, mypltr'Unrestricted_Access, System.Null_Address);
plstyl(mark, space);
plcol0(3);
plcont(w, 1, XPTS, 1, YPTS, clevel, mypltr'Unrestricted_Access, System.Null_Address);
plstyl(0);
plcol0(1);
pllab("X Coordinate", "Y Coordinate", "Streamlines of flow");
-- Plot using 1d coordinate transform
pl_setcontlabelparam(0.006, 0.3, 0.1, False);
plenv(-1.0, 1.0, -1.0, 1.0, 0, 0);
plcol0(2);
plcont(z, 1, XPTS, 1, YPTS, clevel, pltr1'access, cgrid1'Address);
plstyl(mark, space);
plcol0(3);
plcont(w, 1, XPTS, 1, YPTS, clevel, pltr1'access, cgrid1'Address);
plstyl(0);
plcol0(1);
pllab("X Coordinate", "Y Coordinate", "Streamlines of flow");
-- Plot using 2d coordinate transform
plenv(-1.0, 1.0, -1.0, 1.0, 0, 0);
plcol0(2);
plcont(z, 1, XPTS, 1, YPTS, clevel, pltr2'access, cgrid2'Address);
plstyl(mark, space);
plcol0(3);
plcont(w, 1, XPTS, 1, YPTS, clevel, pltr2'access, cgrid2'Address);
plstyl(0);
plcol0(1);
pllab("X Coordinate", "Y Coordinate", "Streamlines of flow");
-- Make polar plot.
pl_setcontlabelparam(0.006, 0.3, 0.1, False);
polar;
-- Make potential plot.
pl_setcontlabelparam(0.006, 0.3, 0.1, False);
potential;
plend;
end x09a;
|