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authorMarius Vollmer <mvo@zagadka.de>2002-05-07 18:11:05 +0000
committerMarius Vollmer <mvo@zagadka.de>2002-05-07 18:11:05 +0000
commit1ee34062aa6a482d3a3cdd957d2f6c59725e97f6 (patch)
tree0b48d30cb3dbddcb3fe4086a3c2967083aeba82a /NEWS
parentcdf52e3dcea4ea0f43a1aef71b7194738aa655b7 (diff)
downloadguile-1ee34062aa6a482d3a3cdd957d2f6c59725e97f6.tar.gz
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@@ -20,6 +20,31 @@ debugging evaluator gives better error messages.
* Changes to Scheme functions and syntax
+** There is support for Infinity and NaNs.
+
+Following PLT Scheme, Guile can now work with infinite numbers, and
+'not-a-numbers'.
+
+There is new syntax for numbers: "+inf.0" (infinity), "-inf.0"
+(negative infinity), "+nan.0" (not-a-number), and "-nan.0" (same as
+"+nan.0"). These numbers are inexact and have no exact counterpart.
+
+Dividing by an inexact zero returns +inf.0 or -inf.0, depending on the
+sign of the dividend. The infinities are integers, and they answer #t
+for both 'even?' and 'odd?'. The +nan.0 value is not an integer and is
+not '=' to itself, but '+nan.0' is 'eqv?' to itself.
+
+For example
+
+ (/ 1 0.0)
+ => +inf.0
+
+ (/ 0 0.0)
+ => +nan.0
+
+ (/ 0)
+ ERROR: Numerical overflow
+
** We now have uninterned symbols.
The new function 'make-symbol' will return a uninterned symbol. This