[CentralOH] 2017-11-23 道場 Scribbles 落書/惡文? 5 approaches to learning Python; WBBY; expr v incr in tcl

[jep200404 at columbus.rr.com]

tcl fibonacci code revisited:

    incr is faster than expr

For the most straightforward version, replacing the expr statement
with an incr statement reduced the execution time.

    jep at casual:~/20171123$ diff fib-with-braces.tcl fib-set-incr.tcl
    7c7,8
    <       set c [expr {$a + $b}]
    ---
    >       set c $a
    >       incr c $b
    jep at casual:~/20171123$ for program in fib-with-braces.tcl fib-with-braces-set-incr.tcl; do echo "$program ======================================================";echo 55555 | ./"$program";done
    fib-with-braces.tcl ======================================================
    Please enter seed value:
    Seed 55555; Result 90963...71278
    Duration 759501 microseconds
    fib-with-braces-set-incr.tcl ======================================================
    Please enter seed value:
    Seed 55555; Result 90963...71278
    Duration 594213 microseconds
    jep at casual:~/20171123$

For the version that used only two variables,
using incr instead of set...expr reduced the execution time,
but was still much slower than the straightforward versions.

    jep at casual:~/20171123$ diff fib-with-braces-without-c.tcl fib-with-braces-incr-without-c.tcl
    7c7
    <       set b [expr {$a + $b}]
    ---
    >       incr b $a
    jep at casual:~/20171123$ for program in fib-without-c.tcl fib-with-braces-incr-without-c.tcl; do echo "$program ======================================================";echo 55555 | ./"$program";done
    fib-without-c.tcl ======================================================
    Please enter seed value:
    Seed 55555; Result 90963...71278
    Duration 1523480 microseconds
    fib-with-braces-incr-without-c.tcl ======================================================
    Please enter seed value:
    Seed 55555; Result 90963...71278
    Duration 1116895 microseconds
    jep at casual:~/20171123$

source code is at the bottom.

===============================================================================

link farm

Wild Bill Bates
http://johnstonteam.blogspot.com/2010/12/wild-bills-seige.html
http://johnstonteam.blogspot.com/2008/01/i-can-kick-higher-than-you-can.html

Finding Files with mlocate: Part 3
https://www.linux.com/blog/learn/2017/11/finding-files-mlocate-part-3

How To Keep A Process/Command Running After Disconnecting SSH Session
https://www.2daygeek.com/how-to-keep-a-process-command-running-after-disconnecting-ssh-session/

LVFS makes Linux firmware updates easier
https://opensource.com/article/17/11/firmware-updates-and-lvfs

Refactoring
https://www.refactoring.com/
part of martinfowler.com

10 Best LaTeX Editors For Linux
https://itsfoss.com/latex-editors-linux/

5 approaches to learning Python
https://opensource.com/article/17/11/5-approaches-learning-python

wp:Four Freedoms
wp:The Free Software Definition

wp: prefix means Wikipedia
To get good answers, consider following the advice in the links below.
http://catb.org/~esr/faqs/smart-questions.html
http://web.archive.org/web/20090627155454/www.greenend.org.uk/rjk/2000/06/14/quoting.html

===============================================================================

source code

    ==> fib-with-braces-incr-without-c.tcl <==
    #!/usr/bin/env tclsh

    proc fib {n} {
       set a 0
       set b 1
       for {set i 0} {$i < $n} {incr i} {
          incr b $a
          set a [expr {$b - $a}]
       }
       return $a
    }

    puts "Please enter seed value:"

    gets stdin x

    set StartTime [clock microseconds]
    set Answer [fib $x]
    set EndTime [clock microseconds]
    puts "Seed $x; Result $Answer"
    puts "Duration [expr $EndTime - $StartTime] microseconds"

    ==> fib-set-incr.tcl <==
    #!/usr/bin/env tclsh

    proc fib {n} {
       set a 0
       set b 1
       for {set i 0} {$i < $n} {incr i} {
          set c $a
          incr c $b
          set a $b
          set b $c
       }
       return $a
    }

    puts "Please enter seed value:"

    gets stdin x

    set StartTime [clock microseconds]
    set Answer [fib $x]
    set EndTime [clock microseconds]
    puts "Seed $x; Result $Answer"
    puts "Duration [expr $EndTime - $StartTime] microseconds"

    ==> fib-with-braces.tcl <==
    #!/usr/bin/env tclsh

    proc fib {n} {
       set a 0
       set b 1
       for {set i 0} {$i < $n} {incr i} {
          set c [expr {$a + $b}]
          set a $b
          set b $c
       }
       return $a
    }

    puts "Please enter seed value:"

    gets stdin x

    set StartTime [clock microseconds]
    set Answer [fib $x]
    set EndTime [clock microseconds]
    puts "Seed $x; Result $Answer"
    puts "Duration [expr $EndTime - $StartTime] microseconds"

    ==> fib-with-braces-without-c.tcl <==
    #!/usr/bin/env tclsh

    proc fib {n} {
       set a 0
       set b 1
       for {set i 0} {$i < $n} {incr i} {
          set b [expr {$a + $b}]
          set a [expr {$b - $a}]
       }
       return $a
    }

    puts "Please enter seed value:"

    gets stdin x

    set StartTime [clock microseconds]
    set Answer [fib $x]
    set EndTime [clock microseconds]
    puts "Seed $x; Result $Answer"
    puts "Duration [expr $EndTime - $StartTime] microseconds"