Re: [TCLCORE] TIP #363: Vector Math in the Tcl Core

[David S. <Dav...@sy...>]

I added Vector/Matrix/Array operators to Tcl about 19 years ago. In doing so I did it with a handle based approach since textually displaying large vectors and mutli-dimensional arrays is not particularly useful. I also added waveforms for EDA at the same time and that deals with large data sets.

The core change was to overload all the operators (plus add a few) to know about the new types. The new operators had to do with defining slices of arrays using a syntactical notation the parser knows about plus some matrix operators.

Doing things with lists I think is not a great idea. The underlying data structure does not support an efficient mechanism for defining slices into large datasets that does duplicate storage. The other incompatible syntax changes are also undesirable.

I can provide more details on this if anyone is interested. I passed it to John O. and Scriptics a long time ago and they did not see a lot of demand for the functionality.

Regards
David

David W. Smith
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-----Original Message-----
From: Neil Madden [mailto:ne...@Cs...] 
Sent: Thursday, March 04, 2010 8:36 AM
To: Alexandre Ferrieux
Cc: tcl...@li...; Karl C. Hansen
Subject: Re: [TCLCORE] TIP #363: Vector Math in the Tcl Core

Alexandre Ferrieux wrote:
> On 3/4/10, Karl C. Hansen <Kar...@br...> wrote:
>>   TIP #363: VECTOR MATH IN THE TCL CORE  
>> =======================================
>>
>>   With the proposed enhancement, and a vector-math core enhancement,
>>   given the assignments above, the following would behave identically:
>>
>>    expr $ListA + {4 5 6}
>>    expr $ListA + $ListB
>>    expr {1 2 3} + $ListB
>>    expr {1 2 3} + {4 5 6}
> 
> So basically you're proposing to break just about everything in Tcl 
> parsing to avoid writing a simple proc for vector/matrix/tensor 
> computations ?
> 
>     proc myexpr {x op y} {
>       if {[llength $x]==1} {return [expr $x $op $b}
>       if {[llength $x]!=[llength $y]} {error "Dimension mismatch"}
>       set z {}
>       foreach a $x b $y {lappend z [myexpr $a $op $b]}
>       return $z
>     }
> 
>    # The following four do the same today without breaking anything:
>    myexpr $ListA + {4 5 6}
>    myexpr $ListA + $ListB
>    myexpr {1 2 3} + $ListB
>    myexpr {1 2 3} + {4 5 6}

Or just Brace Your Exprs (TM) and then write a TIP which actually proposes what the title suggests: adding vector versions of operators to [expr], such that [expr {$ListA + {4 5 6}}] does what makes sense.

-- Neil