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Negative Sign and Infinity _  

The symbol _ followed by a digit denotes a negative number (as in _3.4), and denotes infinity when used alone, or negative infinity (in __). It is also used in names, as discussed in Part I and in Part II Section I.
 

For example:
   2 % 0                      NB. Two divided by zero
_

   10 ^. 0                    NB. Base ten logarithm of zero
__

   _2 _ 3 + 5
3 _ 8

   integer_test=: =<.         NB. Use of break in name
   integer_test 3 3.5
1 0
Although -2 may sometimes be used instead of _2, it is important to understand that the former is the application of a function to the number 2, whereas the symbol _ is an indivisible part of the number representation, just as the period is an indivisible part of a number such as 8.9 .



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