check/genex.cpp

   1 /** @file genex.cpp
   2  *
   3  *  Provides some routines for generating expressions that are later used as
   4  *  input in the consistency checks. */
   5
   6 /*
   7  *  GiNaC Copyright (C) 1999-2002 Johannes Gutenberg University Mainz, Germany
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or
  12  *  (at your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program; if not, write to the Free Software
  21  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  22  */
  23
  24 #include <cstdlib>
  25 #include "ginac.h"
  26 using namespace std;
  27 using namespace GiNaC;
  28
  29 /* Create a dense univariate random polynomial in x.
  30  * (of the form 9 - 22*a - 17*a^2 + 14*a^3 + 7*a^4 + 7a^5 if degree==5) */
  31 const ex
  32 dense_univariate_poly(const symbol & x, unsigned degree)
  33 {
  34         ex unipoly;
  35
  36         for (unsigned i=0; i<=degree; ++i)
  37                 unipoly += numeric((rand()-RAND_MAX/2))*pow(x,i);
  38
  39         return unipoly;
  40 }
  41
  42 /* Create a dense bivariate random polynomial in x1 and x2.
  43  * (of the form 9 + 52*x1 - 27*x1^2 + 84*x2 + 7*x2^2 - 12*x1*x2 if degree==2)
  44  */
  45 const ex
  46 dense_bivariate_poly(const symbol & x1, const symbol & x2, unsigned degree)
  47 {
  48         ex bipoly;
  49
  50         for (unsigned i1=0; i1<=degree; ++i1)
  51                 for (unsigned i2=0; i2<=degree-i1; ++i2)
  52                         bipoly += numeric((rand()-RAND_MAX/2))*pow(x1,i1)*pow(x2,i2);
  53
  54         return bipoly;
  55 }
  56
  57 /* Chose a randum symbol or number from the argument list. */
  58 const ex
  59 random_symbol(const symbol & x,
  60                           const symbol & y,
  61                           const symbol & z,
  62                           bool rational = true,
  63                           bool complex = false)
  64 {
  65         ex e;
  66         switch (abs(rand()) % 4) {
  67                 case 0:
  68                         e = x;
  69                         break;
  70                 case 1:
  71                         e = y;
  72                         break;
  73                 case 2:
  74                         e = z;
  75                         break;
  76                 case 3: {
  77                         int c1;
  78                         do { c1 = rand()%20 - 10; } while (!c1);
  79                         int c2;
  80                         do { c2 = rand()%20 - 10; } while (!c2);
  81                         if (!rational)
  82                                 c2 = 1;
  83                         e = numeric(c1, c2);
  84                         if (complex && !(rand()%5))
  85                                 e = e*I;
  86                         break;
  87                 }
  88         }
  89         return e;
  90 }
  91
  92 /* Create a sparse random tree in three symbols. */
  93 const ex
  94 sparse_tree(const symbol & x,
  95                         const symbol & y,
  96                         const symbol & z,
  97                         int level,
  98                         bool trig = false,      // true includes trigonomatric functions
  99                         bool rational = true, // false excludes coefficients in Q
 100                         bool complex = false) // true includes complex numbers
 101 {
 102         if (level == 0)
 103                 return random_symbol(x,y,z,rational,complex);
 104         switch (abs(rand()) % 10) {
 105                 case 0:
 106                 case 1:
 107                 case 2:
 108                 case 3:
 109                         return add(sparse_tree(x,y,z,level-1, trig, rational),
 110                                            sparse_tree(x,y,z,level-1, trig, rational));
 111                 case 4:
 112                 case 5:
 113                 case 6:
 114                         return mul(sparse_tree(x,y,z,level-1, trig, rational),
 115                                            sparse_tree(x,y,z,level-1, trig, rational));
 116                 case 7:
 117                 case 8: {
 118                         ex powbase;
 119                         do {
 120                                 powbase = sparse_tree(x,y,z,level-1, trig, rational);
 121                         } while (powbase.is_zero());
 122                         return pow(powbase, abs(rand() % 4));
 123                         break;
 124                 }
 125                 case 9:
 126                         if (trig) {
 127                                 switch (abs(rand()) % 4) {
 128                                         case 0:
 129                                                 return sin(sparse_tree(x,y,z,level-1, trig, rational));
 130                                         case 1:
 131                                                 return cos(sparse_tree(x,y,z,level-1, trig, rational));
 132                                         case 2:
 133                                                 return exp(sparse_tree(x,y,z,level-1, trig, rational));
 134                                         case 3: {
 135                                                 ex logex;
 136                                                 do {
 137                                                         ex logarg;
 138                                                         do {
 139                                                                 logarg = sparse_tree(x,y,z,level-1, trig, rational);
 140                                                         } while (logarg.is_zero());
 141                                                         // Keep the evaluator from accidentally plugging an
 142                                                         // unwanted I in the tree:
 143                                                         if (!complex && logarg.info(info_flags::negative))
 144                                                                 logarg = -logarg;
 145                                                         logex = log(logarg);
 146                                                 } while (logex.is_zero());
 147                                                 return logex;
 148                                                 break;
 149                                         }
 150                                 }
 151                         } else
 152                                 return random_symbol(x,y,z,rational,complex);
 153         }
 154 }