[PATCH 1/3] Automatic evaluation of (e^t)^s = e^(ts).

[ginac.git] / check / exam_misc.cpp

diff --git a/check/exam_misc.cpp b/check/exam_misc.cpp
index 10c3dc46fb2ce052d4b5a0c104432941d07b04d5..8c28fb5344edcde971182e42616bb75b5f721381 100644 (file)
--- a/check/exam_misc.cpp
+++ b/check/exam_misc.cpp
@@ -3,7 +3,7 @@
  */
 
 /*
- *  GiNaC Copyright (C) 1999-2009 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2020 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -89,49 +89,6 @@ static unsigned exam_expand_power()
        return result;
 }
 
-static unsigned exam_sqrfree()
-{
-       unsigned result = 0;
-       symbol x("x"), y("y");
-       ex e1, e2;
-       
-       e1 = (1+x)*pow((2+x),2)*pow((3+x),3)*pow((4+x),4);
-       e2 = sqrfree(expand(e1),lst(x));
-       if (e1 != e2) {
-               clog << "sqrfree(expand(" << e1 << ")) erroneously returned "
-                    << e2 << endl;
-               ++result;
-       }
-       
-       e1 = (x+y)*pow((x+2*y),2)*pow((x+3*y),3)*pow((x+4*y),4);
-       e2 = sqrfree(expand(e1));
-       if (e1 != e2) {
-               clog << "sqrfree(expand(" << e1 << ")) erroneously returned "
-                    << e2 << endl;
-               ++result;
-       }
-       e2 = sqrfree(expand(e1),lst(x));
-       if (e1 != e2) {
-               clog << "sqrfree(expand(" << e1 << "),[x]) erroneously returned "
-                    << e2 << endl;
-               ++result;
-       }
-       e2 = sqrfree(expand(e1),lst(y));
-       if (e1 != e2) {
-               clog << "sqrfree(expand(" << e1 << "),[y]) erroneously returned "
-                    << e2 << endl;
-               ++result;
-       }
-       e2 = sqrfree(expand(e1),lst(x,y));
-       if (e1 != e2) {
-               clog << "sqrfree(expand(" << e1 << "),[x,y]) erroneously returned "
-                    << e2 << endl;
-               ++result;
-       }
-       
-       return result;
-}
-
 /* Arithmetic Operators should behave just as one expects from built-in types.
  * When somebody screws up the operators this routine will most probably fail
  * to compile.  Unfortunately we can only test the stuff that is allowed, not
@@ -164,7 +121,7 @@ static unsigned exam_operator_semantics()
                ++result;
        }
        
-       // Prefix/postfix increment/decrement behaviour:
+       // Prefix/postfix increment/decrement behavior:
        e1 = 7; e2 = 4;
        i1 = 7; i2 = 4;
        e1 = (--e2 = 2)++;
@@ -219,6 +176,15 @@ static unsigned exam_subs()
                ++result;
        }
 
+       // And this used to fail in GiNaC 1.5.8 because it first substituted
+       // exp(x) -> exp(log(x)) -> x, and then substituted again x -> log(x)
+       e1 = exp(x);
+       e2 = e1.subs(x == log(x));
+       if (!e2.is_equal(x)) {
+               clog << "exp(x).subs(x==log(x)) erroneously returned " << e2 << " instead of x" << endl;
+               ++result;
+       }
+
        e1 = sin(1+sin(x));
        e2 = e1.subs(sin(wild()) == cos(wild()));
        if (!e2.is_equal(cos(1+cos(x)))) {
@@ -289,6 +255,29 @@ static unsigned exam_subs_algebraic()
        return result;
 }
 
+/* Test suitable cases of the exponent power law: (e^t)^s=e^(ts). */
+static unsigned exam_exponent_power_law()
+{
+       unsigned result = 0;
+       symbol x("x");
+       realsymbol s("s");
+       possymbol t("t");
+
+       exmap pwr_exp =
+               { {pow(exp(x), 2), exp(2*x)},
+                 {pow(exp(s), t), exp(s*t)},
+                 {exp(x)*pow(exp(x),-1), 1} };
+
+       for (auto e : pwr_exp) {
+               if (! (e.first.is_equal(e.second)) ) {
+                       clog << "power of exponent  " << e.first << " produces error.\n";
+                       ++result;
+               }
+       }
+
+       return result;
+}
+
 unsigned exam_misc()
 {
        unsigned result = 0;
@@ -298,11 +287,11 @@ unsigned exam_misc()
        result += exam_expand_subs();  cout << '.' << flush;
        result += exam_expand_subs2();  cout << '.' << flush;
        result += exam_expand_power(); cout << '.' << flush;
-       result += exam_sqrfree(); cout << '.' << flush;
        result += exam_operator_semantics(); cout << '.' << flush;
        result += exam_subs(); cout << '.' << flush;
        result += exam_joris(); cout << '.' << flush;
        result += exam_subs_algebraic(); cout << '.' << flush;
+       result += exam_exponent_power_law(); cout << '.' << flush;
        
        return result;
 }