Tutorial: how to create noncommutative symbols?

[ginac.git] / doc / tutorial / ginac.texi

diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi
index 360acb05a0e98b1a38f8923f7b43920aa266cabc..93ed619ffc4c87b0e82de5b4fdaed6119d9e930f 100644 (file)
--- a/doc/tutorial/ginac.texi
+++ b/doc/tutorial/ginac.texi
@@ -3033,6 +3033,8 @@ canonicalize themselves according to rules specified in the implementation
 of the non-commutative classes. The drawback is that to work with other than
 the built-in algebras you have to implement new classes yourself. Both
 symbols and user-defined functions can be specified as being non-commutative.
+For symbols, this is done by subclassing class symbol; for functions,
+by explicitly setting the return type (@pxref{Symbolic functions}).
 
 @cindex @code{return_type()}
 @cindex @code{return_type_tinfo()}
@@ -6505,7 +6507,7 @@ to map input (sub)strings to arbitrary expressions:
     table["x"] = x+log(y)+1;
     parser reader(table);
     ex e = reader("5*x^3 - x^2");
-    // e = 5*(x+log(y)+1)^3 + (x+log(y)+1)^2
+    // e = 5*(x+log(y)+1)^3 - (x+log(y)+1)^2
 @}
 @end example
 
@@ -6518,8 +6520,8 @@ with @code{get_syms()} method:
     parser reader;
     ex e = reader("2*x+sin(y)");
     symtab table = reader.get_syms();
-    symbol x = reader["x"];
-    symbol y = reader["y"];
+    symbol x = ex_to<symbol>(table["x"]);
+    symbol y = ex_to<symbol>(table["y"]);
 @}
 @end example
 
@@ -6692,7 +6694,13 @@ ones supplied to @code{compile_ex} should appear in the expression.
 @code{compile_ex} uses the shell script @code{ginac-excompiler} to start the C
 compiler and produce the object files. This shell script comes with GiNaC and
 will be installed together with GiNaC in the configured @code{$PREFIX/bin}
-directory.
+directory. You can also export additional compiler flags via the $CXXFLAGS
+variable:
+
+@example
+setenv("CXXFLAGS", "-O3 -fomit-frame-pointer -ffast-math", 1);
+compile_ex(...);
+@end example
 
 @subsection Archiving
 @cindex @code{archive} (class)