Calculating Event Horizons in Ruby

Question

this is my first post here. I started using Ruby just 2 days ago and think it is an amazing language, however I have been getting stuck. My problem is I am wanting to calculate the event horizon of a black hole given an input defined in the code as "m" This will then be put into a calculation and the size then printed out to the screen. I did need it to be in binary and thats where I am having the issue.

Here is my code so far.

#Event Horizon Calculation Program
G = 6.67*10**-11
m = 20
C = 200000

R = G*m/(C**2)

puts "Here is the result in Binary."

R.to_i(2)

puts R

Now I do realise that the number are not accurate, that dosen't matter at the moment. I just need the function to work.

Thankyou,

Ross.

The .to_i method won't accept any argument... can you try with R.to_i instead. — ssri, Mar 09 '11 at 12:07
For debugging hints, you may also want to see http://stackoverflow.com/questions/3955688/how-do-i-debug-ruby-scripts — Andrew Grimm, Mar 09 '11 at 22:27

score 1 · Accepted Answer · answered Mar 09 '11 at 12:18

Your post is not even in a format of asking a question, but guessing from what you wrote, it seems that you are asking how to change your code so that it accepts an input to m and outputs the result. My answer is based on this assumption.

In order to take an input, use the 'gets' method. So, you may want to replace your 'm = 20' line with:

m = gets.to_f

'gets' accepts an input as a string, so you need to convert it to a numeric. to_f changes a string into a float. You can use to_i instead if you want an integer.

You have a line 'R.to_i(2)', and it seems like you want to output this, but you have two problems here. First of all, whatever that creates, it is only creating something in that position, and does not change the value of R, so, in effect, it actually does nothing. Second, ruby can accept numerals in source code written in different bases such decimal, binary, hex, etc., but it only has one internal representation, and you cannot output a numeral in binary. For your purpose, you need to convert it to a string that corresponds to a binary expression. For that, use the 'to_s' method. In fact, the 'to_i' method does not take an argument. Delete your line 'R.to_i(s)', and replace the line 'puts R' with:

puts R.to_s(2)

Calculating Event Horizons in Ruby

1 Answers1