* Fix citation.

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

diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi
index 241de6761f8ce1bc0528f6d86fddd4b288033a7e..54a373433ab5615281dd3f598cec62b1e69bf3d4 100644 (file)
--- a/doc/tutorial/ginac.texi
+++ b/doc/tutorial/ginac.texi
@@ -1878,9 +1878,9 @@ indices into a canonical order which allows for some immediate simplifications:
      // -> 2*A.j.i
     cout << indexed(B, sy_anti(), i, j)
           + indexed(B, sy_anti(), j, i) << endl;
-     // -> -B.j.i
+     // -> 0
     cout << indexed(B, sy_anti(), i, j, k)
-          + indexed(B, sy_anti(), j, i, k) << endl;
+          - indexed(B, sy_anti(), j, k, i) << endl;
      // -> 0
     ...
 @end example
@@ -1895,8 +1895,8 @@ not dummy indices are called @dfn{free indices}. Numeric indices are neither
 dummy nor free indices.
 
 To be recognized as a dummy index pair, the two indices must be of the same
-class and dimension and their value must be the same single symbol (an index
-like @samp{2*n+1} is never a dummy index). If the indices are of class
+class and their value must be the same single symbol (an index like
+@samp{2*n+1} is never a dummy index). If the indices are of class
 @code{varidx} they must also be of opposite variance; if they are of class
 @code{spinidx} they must be both dotted or both undotted.
 
@@ -3898,14 +3898,14 @@ Only calling the series method makes the last output simplify to
 @math{1-v^2/c^2+O(v^10)}, without that call we would just have a long
 series raised to the power @math{-2}.
 
-@cindex M@'echain's formula
+@cindex Machin's formula
 As another instructive application, let us calculate the numerical 
 value of Archimedes' constant
 @tex
 $\pi$
 @end tex
 (for which there already exists the built-in constant @code{Pi}) 
-using M@'echain's amazing formula
+using Machin's amazing formula
 @tex
 $\pi=16$~atan~$\!\left(1 \over 5 \right)-4$~atan~$\!\left(1 \over 239 \right)$.
 @end tex
@@ -3923,7 +3923,7 @@ the order term off:
 #include <ginac/ginac.h>
 using namespace GiNaC;
 
-ex mechain_pi(int degr)
+ex machin_pi(int degr)
 @{
     symbol x;
     ex pi_expansion = series_to_poly(atan(x).series(x,degr));
@@ -3938,7 +3938,7 @@ int main()
     using std::endl;  // ...dealing with this namespace std.
     ex pi_frac;
     for (int i=2; i<12; i+=2) @{
-        pi_frac = mechain_pi(i);
+        pi_frac = machin_pi(i);
         cout << i << ":\t" << pi_frac << endl
              << "\t" << pi_frac.evalf() << endl;
     @}
@@ -4298,19 +4298,22 @@ and have the @samp{x} and @samp{y} correspond to the symbols @code{x} and
 desired symbols to the @code{>>} stream input operator.
 
 Instead, GiNaC lets you construct an expression from a string, specifying the
-list of symbols to be used:
+list of symbols and indices to be used:
 
 @example
 @{
-    symbol x("x"), y("y");
-    ex e("2*x+sin(y)", lst(x, y));
+    symbol x("x"), y("y"), p("p");
+    idx i(symbol("i"), 3);
+    ex e("2*x+sin(y)+p.i", lst(x, y, p, i));
 @}
 @end example
 
 The input syntax is the same as that used by @command{ginsh} and the stream
-output operator @code{<<}. The symbols in the string are matched by name to
-the symbols in the list and if GiNaC encounters a symbol not specified in
-the list it will throw an exception.
+output operator @code{<<}. The symbols and indices in the string are matched
+by name to the symbols and indices in the list and if GiNaC encounters a
+symbol or index not specified in the list it will throw an exception. Only
+indices whose values are single symbols can be used (i.e. numeric indices
+or compound indices as in "A.(2*n+1)" are not allowed).
 
 With this constructor, it's also easy to implement interactive GiNaC programs: