From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2009-11-06T01:21:56+09:00
Subject: Re: question about variables in ruby

On Thu, Nov 5, 2009 at 1:18 PM, Mahadev Ittina <mittina@gmail.com> wrote:
> hello folks i am preparing a ruby plugin for sketchup, i hope you can
> help me with this really nasty problem i am having
>
> here is the method ,which belongs to a class
>
>  def moment_calc
>
>    weight = 0
>    variable_load = 0
>    permanent_load = 0
>    moment = 0
>
>    weight =((25.0*@b*@h) / 10**6)
>    prompts = ["Variable Load(kN/m) ", "Permanent Load(kN/m) ", "Max
> Moment known(Nmm)"]
>    loads = [0.0, 0.0, 0.0]
>    results = inputbox prompts, loads, "Other Loads"
>    variable_load, permanent_load, moment = results
>
>    if (moment != 0)
>      @M = moment
>    else
>      uls = (1.35*variable_load + 1.5*permanent_load +
> 1.5*weight)*@length
>      @M = 0.11*uls*@length
>      @shear = 0.60 * uls
>    end
>  end
>
> my @b = 280 and @h=300 from before.. when i try to multiply the weight
> it should come 2.1 but in this case it is 0.0032 or so.. which is
> wrong.. hence because of that my uls values are wrong and hence the
> entire following program.. i am pretty sure its problem with the
> variables.. just cant figure out where!

irb(main):001:0> @b = 280
=> 280
irb(main):002:0> @h = 300
=> 300
irb(main):003:0> weight =((25.0*@b*@h) / 10**6)
=> 2.1

This calculation is correct: 2.1, so if you are getting a different
result it has to be that @b or @h don't contain what you think they
do. Can you try to print @b, @h and weight, and show us the calling
code that produces weight being 0.00032?

def moment_calc
  puts "@b is #{@b}"
  puts "@h is #{@h}"
  weight =((25.0*@b*@h) / 10**6)
  puts "weight is #{weight}"
end

If you put this in your program, what happens?

Also, you don't need this:

>    weight = 0
>    variable_load = 0
>    permanent_load = 0
>    moment = 0

in Ruby you don't need to declare your variables before assigning
(another value) to them. So assigning them a 0 only to assign them
another value afterwards is not needed.

Jesus.