• bono u2.art (50/58) Aug 19 2003 The simbols used for operator dealing with nan in floating point express...
• Walter (9/67) Aug 23 2003 I know they're a bit complicated. They do match, however, the NCEG propo...

bono u2.art writes:

The simbols used for operator dealing with nan in floating point expression are
dificult to learn and remember and is easy to confuse.
Programer must use the reverse logic to find the meaning of the operator.
But with a direct logic this problems, IMHO, could be simpler.
The main idea is add the char '?' when dealing with nans

Current table of Operators:

Operator	Greater		Less Than	Equal		Unordered	Exception	Relation
---------------------------------------------------------------------------------------------------
==			F			F			T			F			no			equal			
!=			T			T			F			T			no			unordered, less, or greater			
			T			F			F			F			yes			greater			
=			T			F			T			F			yes			greater or equal			

<			F			T			F			F			yes			less			
<=			F			T			T			F			yes			less or equal			
!<>=		F			F			F			T			no			unordered			
<>			T			T			F			F			yes			less or greater			
<>=			T			T			T			F			yes			less, equal, or greater			
!<=			T			F			F			T			no			unordered or greater			
!<			T			F			T			T			no			unordered, greater, or equal			
!>=			F			T			F			T			no			unordered or less			
!>			F			T			T			T			no			unordered, less, or equal			
!<>			F			F			T			T			no			unordered or equal			

The simbols to change:

New 		Current		Relation
-----------------------------------------------------
?=			!<>=		unordered
?			!<=			unordered or greater
=?			!<			unordered, greater, or equal

<?			!>=			unordered or less
<=?			!>			unordered, less, or equal
==?			!<>			unordered or equal

The new table of Operators:

Operator	Greater		Less Than	Equal		Unordered	Exception	Relation
---------------------------------------------------------------------------------------------------
==			F			F			T			F			no			equal			
!=			T			T			F			T			no			unordered, less, or greater			
			T			F			F			F			yes			greater			
=			T			F			T			F			yes			greater or equal			

<			F			T			F			F			yes			less			
<=			F			T			T			F			yes			less or equal			
<>			T			T			F			F			yes			less or greater			
<>=			T			T			T			F			yes			less, equal, or greater			
?=			F			F			F			T			no			unordered			
==?			F			F			T			T			no			equal or unordered			
?			T			F			F			T			no			greater	or unordered			
=?			T			F			T			T			no			greater, equal, or unordered

<?			F			T			F			T			no			less or unordered
<=?			F			T			T			T			no			less, equal, or unordered

The are motivation for this change are:

a) The same operator as integer expressions are used for normal comparison (call
this basic operators):

== != > >= < <=

b) When the operator contains < or > and one of the one of the operands is a NAN
then a exception is raised.
c) To deal with NAN you add the '?' after the normal operator
d) There are two more operators: <> and <>=

This rule is simpler, IMHO.

Comments ?

"Walter" <walter digitalmars.com> writes:

I know they're a bit complicated. They do match, however, the NCEG proposed
extensions to C (which were never adopted). Your idea has merit, I need to
think about it.

<bono u2.art> wrote in message news:bhtfsr$1sgt$1 digitaldaemon.com...
 The simbols used for operator dealing with nan in floating point

expression are
 dificult to learn and remember and is easy to confuse.
 Programer must use the reverse logic to find the meaning of the operator.
 But with a direct logic this problems, IMHO, could be simpler.
 The main idea is add the char '?' when dealing with nans

 Current table of Operators:

 Operator Greater Less Than Equal Unordered Exception Relation
 --------------------------------------------------------------------------

-------------------------
 == F F T F no equal
 != T T F T no unordered, less, or greater
 T F F F yes greater
= T F T F yes greater or equal

 < F T F F yes less
 <= F T T F yes less or equal
 !<>= F F F T no unordered
 <> T T F F yes less or greater
 <>= T T T F yes less, equal, or greater
 !<= T F F T no unordered or greater
 !< T F T T no unordered, greater, or equal
 !>= F T F T no unordered or less
 !> F T T T no unordered, less, or equal
 !<> F F T T no unordered or equal

 The simbols to change:

 New Current Relation
 -----------------------------------------------------
 ?= !<>= unordered
? !<= unordered or greater
=? !< unordered, greater, or equal

 <? !>= unordered or less
 <=? !> unordered, less, or equal
 ==? !<> unordered or equal

 The new table of Operators:

 Operator Greater Less Than Equal Unordered Exception Relation
 --------------------------------------------------------------------------

-------------------------
 == F F T F no equal
 != T T F T no unordered, less, or greater
 T F F F yes greater
= T F T F yes greater or equal

 < F T F F yes less
 <= F T T F yes less or equal
 <> T T F F yes less or greater
 <>= T T T F yes less, equal, or greater
 ?= F F F T no unordered
 ==? F F T T no equal or unordered
? T F F T no greater or unordered
=? T F T T no greater, equal, or unordered

 <? F T F T no less or unordered
 <=? F T T T no less, equal, or unordered

 The are motivation for this change are:

 a) The same operator as integer expressions are used for normal comparison

(call
 this basic operators):

 == != > >= < <=

 b) When the operator contains < or > and one of the one of the operands is

a NAN
 then a exception is raised.
 c) To deal with NAN you add the '?' after the normal operator
 d) There are two more operators: <> and <>=

 This rule is simpler, IMHO.

 Comments ?