Re: Procedure for percent of a value

Marcos Martinez Sancho wrote:
Hello,

I need a small procedure for calculate the percent of a value

e.g.


set srate [expr int(($tps_ok / $number_of_total_tps)*100)]

puts "\nTEST RESULT: $number_of_total_tps tps of which $tps_ok PASSED and $tps_nok FAILED so $srate % succes rate"


doesnt look optimal and is not working except when srate = 100%. Otherwise, I get 0%.

When both numbers in a division operation are are integer, [expr] performs an integer division. That means that only the integer part of the result is calculated, no "comma part":

% expr 10/3
3
%

And since srate < 100% means that tps_ok is less than number_of_total_tps, the $tps_ok / $number_of_total_tps will always give 0 as result.

The solution is to make one of the values a floating point value, all other numbers will be "coerced" into floating point numbers too. Usually it's done like this:

set srate [expr int((1.0 * $tps_ok / $number_of_total_tps)*100)]
^^



Any input is appreciated.

Thanks


Marcos


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Relevant Pages

  • Re: Procedure for percent of a value
    ... old fogies who have done a lot of work on integer only systems is ... to multiply first ie.g. ... doesnt look optimal and is not working except when srate = 100%. ... The solution is to make one of the values a floating point value, all other numbers will be "coerced" into floating point numbers too. ...
    (comp.lang.tcl)
  • Re: Procedure for percent of a value
    ... doesnt look optimal and is not working except when srate = 100%. ... When both numbers in a division operation are are integer, [expr] ... The solution is to make one of the values a floating point value, ... 'Everybody understand that floating point calculations are NOT ...
    (comp.lang.tcl)
  • Re: Procedure for percent of a value
    ... $tps_nok FAILED so $srate % succes rate" ... doesnt look optimal and is not working except when srate = 100%. ... You need to ensure floating point division as others have indicated. ...
    (comp.lang.tcl)