From: Richard Kreckel Date: Mon, 10 Apr 2000 17:20:36 +0000 (+0000) Subject: - De-mystified the chapter about relationals. X-Git-Tag: release_0-6-0~23 X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=commitdiff_plain;h=b40bb4ef533e40d4cd619b74fc2916a5255fd633 - De-mystified the chapter about relationals. --- diff --git a/doc/tutorial/ginac.texi b/doc/tutorial/ginac.texi index 06e4a8ca..e43b4bb3 100644 --- a/doc/tutorial/ginac.texi +++ b/doc/tutorial/ginac.texi @@ -1232,13 +1232,19 @@ a relation between them that signals equality, inequality and so on. They are created by simply using the C++ operators @code{==}, @code{!=}, @code{<}, @code{<=}, @code{>} and @code{>=} between two expressions. -@xref{Mathematical functions}, for examples where various applications of -the @code{.subs()} method show how objects of class relational are used -as arguments. There they provide an intuitive syntax for substitutions. -They can also used for creating systems of equations that are to be -solved for unknown variables. More applications of this class will -appear throughout the next chapters. - +@xref{Mathematical functions}, for examples where various applications +of the @code{.subs()} method show how objects of class relational are +used as arguments. There they provide an intuitive syntax for +substitutions. They are also used as arguments to the @code{ex::series} +method, where the left hand side of the relation specifies the variable +to expand in and the right hand side the expansion point. They can also +be used for creating systems of equations that are to be solved for +unknown variables. But the most common usage of objects of this class +is rather inconspicuous in statements of the form @code{if +(expand(pow(a+b,2))==a*a+2*a*b+b*b) @{...@}}. Here, an implicit +conversion from @code{relational} to @code{bool} takes place. Note, +however, that @code{==} here does not perform any simplifications, hence +@code{expand()} must be called explicitly. @node Methods and Functions, Information About Expressions, Relations, Top