mentioned ncpow()

diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi
index 12d7035d67d9432c0fbbf22e839743402dad0026..c5841b8a5bd062a7dc050fa7d78abef2331e97a6 100644 (file)
--- a/doc/tutorial/ginac.texi
+++ b/doc/tutorial/ginac.texi
@@ -1970,6 +1970,16 @@ Other representation labels yield a different @code{return_type_tinfo()},
 but it's the same for any two objects with the same label. This is also true
 for color objects.
 
 but it's the same for any two objects with the same label. This is also true
 for color objects.
 

+As a last note, powers of non-commutative objects are not allowed in GiNaC.
+You can use the function
+
+@example
+ex ncpow(const ex & basis, unsigned exponent)
+@end example
+
+instead which returns an expanded product (e.g. @code{ncpow(a*b, 2)} becomes
+@samp{a*b*a*b} if @samp{a} and @samp{b} are non-commutative expressions).
+

 
 @cindex @code{clifford} (class)
 @subsection Clifford algebra
 
 @cindex @code{clifford} (class)
 @subsection Clifford algebra


@@ -2799,7 +2809,7 @@ The last example would be written in C++ in this way:
     e = a*pow(sin(x+y), 2) + a*pow(cos(x+y), 2) + b;
     e = e.subs(pow(cos(wild()), 2) == 1-pow(sin(wild()), 2));
     cout << e.expand() << endl;
     e = a*pow(sin(x+y), 2) + a*pow(cos(x+y), 2) + b;
     e = e.subs(pow(cos(wild()), 2) == 1-pow(sin(wild()), 2));
     cout << e.expand() << endl;

-     // -> "b+a"
+     // -> a+b

 @}
 @end example
 
 @}
 @end example