Ruby module error

Ruby
1

How in ruby i can write module ?
so we have:
a=-4
b=-9

g = Math.sqrt(Math.Module(a))(Math.Module(b))
def g(a, b)
Math.sqrt(Math.Module(a))(Math.Module(b))
end

end when i write “puts g” i have a error. I try write Math.mod but
nothing.
“rb:4: undefined method `Module’ for Math:Module (NoMethodError)”

g = (Math.sqrt|a|*|b|) #<= doest work too

2

On Sat, Dec 10, 2011 at 12:39 PM, Vadim P. [email protected]
wrote:

end when i write “puts g” i have a error. I try write Math.mod but
nothing.
“rb:4: undefined method `Module’ for Math:Module (NoMethodError)”

For the module Math, you can easily see the documented
instance and class methods with

$ ri Math

The term “Module” is not one of them, so that is why you
get the error:
“undefined method `Module’ for Math:Module (NoMethodError)”

You can use the module methods with

Math.sin(0.75)

You can use the instance methods with

include Math
sin(0.75)

Regarding your question how to write a module,
as example, I have written an Average module:

peterv@ASUS:~$ cat average.rb
module Average
def geometric(*a)
case a.size
when 0
raise “At least one argument required”
when 1
a[0]
when 2
Math.sqrt(a[0]a[1])
else
(a.inject(1){|acc,e| acce})**(1.0/a.size)
end
end

def arithmetic(*a)
case a.size
when 0
raise “At least one argument required”
when 1
a[0]
else
(a.inject(0){|acc,e| acc+e})/Float(a.size) # force a float
end
end
end

and when I ‘include’ that, I can use the methods as instance
methods (on main).

An alternative would have been to define both methods as
module methods (with “def self.geometric”). This would have
the advantage of avoiding polluting the general name space
with the “include Average” .

peterv@ASUS:~$ irb
001:0> require ‘average’
=> true
002:0> include Average
=> Object
003:0> geometric()
RuntimeError: At least one argument required
from ./average.rb:5:in geometric' from (irb):3 004:0> geometric(4) => 4 005:0> geometric(4,9) => 6.0 006:0> geometric(4,9,48) => 12.0 007:0> arithmetic() RuntimeError: At least one argument required from ./average.rb:18:in arithmetic’
from (irb):7
008:0> arithmetic(7)
=> 7
009:0> arithmetic(4,7)
=> 5.5
010:0> arithmetic(4,7,6,9)
=> 6.5

In my “Average” module, I have now used the Math.sqrt
module function of the Math module to demonstrate the
proper use of such a module function.

HTH,

Peter

3

a = -4
b = -9

g = Math.sqrt(a * b)

puts g

  • j
4

I try write Math.mod

You should use

def self.mod

Like:

module Math
def self.mod
# add your code here
end
end