----- Original Message ----- From: "Jean-Claude Wippler" <[EMAIL PROTECTED]>
To: "Metakit list" <[email protected]>
Sent: Monday, May 09, 2005 11:30 AM
Subject: Re: [Metakit] Performance comparison Q
[EMAIL PROTECTED] wrote:
If you have the data in an array
No, list (Tcl arrays are hash tables, I am interested in vector access).
% time {for {set i 0} {$i < 49999} {incr i} {incr sum [lindex $data $i]}} 10
198283 microseconds per iteration
Fascinating. I dismissed this one and used foreach, which is slower. Still under 1% of C.
-jcw
How about the following:
Jeff
proc sum1 {} {
set sum 0
foreach int $::intList {incr sum $int}
}proc sum2 {} {
set sum 0
for {set i 0} {$i < 50000} {incr i} {
incr sum [lindex $::intList $i]
}
}proc sum3 {intList} {
set sum 0
foreach int $intList {incr sum $int}
}proc sum4 {intList} {
set sum 0
for {set i 0} {$i < 50000} {incr i} {
incr sum [lindex $intList $i]
}
}catch {console show}# --- load the initial list with values
set intList [list]
for {set i 0} {$i < 50000} {incr i} {
lappend intList $i
}# --- Now, time various methods of summing the data...
puts "sum1 --> [time sum1 25]" puts "sum2 --> [time sum2 25]" puts "sum3 --> [time [list sum3 $intList] 25]" puts "sum4 --> [time [list sum4 $intList] 25]"
Results...
sum1 --> 11164 microseconds per iteration sum2 --> 36158 microseconds per iteration sum3 --> 15525 microseconds per iteration sum4 --> 21157 microseconds per iteration
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