Initial revision

[ginac.git] / check / expand_subs.cpp

diff --git a/check/expand_subs.cpp b/check/expand_subs.cpp
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+// check/expand_subs.cpp
+
+/* The first test routine implements Denny Fliegner's quick consistency check:
+ *     e = (a0 + a1 + a2 + a3 + ...)^2
+ *     expand e
+ *     substitute a0 by (-a2 - a3 - ...) in e
+ *     expand e
+ * after which e should be just a1^2.
+ * In addition, a simpler modification is tested in the second test:
+ *     e = (a0 + a1)^200
+ *     expand e
+ *     substitute a0 by -a1 in e
+ * after which e should return 0 (without expanding). */
+
+#include "ginac.h"
+
+#define VECSIZE 100
+
+static unsigned expand_subs1(void)
+{
+    symbol a1("a1");
+    symbol a[VECSIZE];
+    ex e, aux;
+
+    a[1] = a1;
+    for (unsigned i=0; i<VECSIZE; ++i) {
+        e = e + a[i];
+    }
+
+    // prepare aux so it will swallow anything but a1^2:
+    aux = -e + a[0] + a[1];
+    e = expand(subs(expand(pow(e, 2)), a[0] == aux));
+
+    if (e != pow(a1,2)) {
+        clog << "Denny Fliegner's quick consistency check erroneously returned "
+             << e << "." << endl;
+        return 1;
+    }
+    return 0;
+}
+
+static unsigned expand_subs2(void)
+{
+    symbol a("a"), b("b");
+    ex e, f;
+
+    // Here the final expand() should be superflous. For no particular reason
+    // at all, we don't use the wrapper-functions but the methods instead:
+    e = pow(a+b,200).expand();
+    f = e.subs(a == -b);
+
+    if (f != 0) {
+        clog << "e = pow(a+b,200).expand(); f = e.subs(a == -b); erroneously returned "
+             << f << " instead of simplifying to 0." << endl;
+        return 1;
+    }
+    return 0;
+}
+
+unsigned expand_subs(void)
+{
+    unsigned result = 0;
+
+    cout << "checking commutative expansion and substitution..." << flush;
+    clog << "---------commutative expansion and substitution:" << endl;
+
+    result += expand_subs1();
+    result += expand_subs2();
+
+    if (! result) {
+        cout << " passed ";
+        clog << "(no output)" << endl;
+    } else {
+        cout << " failed ";
+    }
+
+    return result;
+}