This week's book giveaway is in the Other Languages forum.
We're giving away four copies of Functional Reactive Programming and have Stephen Blackheath and Anthony Jones on-line!
See this thread for details.
Win a copy of Functional Reactive Programming this week in the Other Languages forum!
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

Math.random() & .round() question from RHE

 
Trevor Green
Ranch Hand
Posts: 44
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
A question from RHE is:
"What is the value of the following expression?
Math.round(Math.random() + 2.50001);"
Answers: A) 2; B) 3; C) It is impossible to say.
The answer is 3 (not "It is impossible to say").
This implies that you cannot get a result of 3.5
The implication of this is that Math.random() won't return .99999. I realise it's result is 0<=x<1.0. So is the result only to four decimal places (ie max value is 0.9999)?
 
Jyotsna Umesh
Ranch Hand
Posts: 94
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Originally posted by Trevor Green:
A question from RHE is:
"What is the value of the following expression?
Math.round(Math.random() + 2.50001);"
Answers: A) 2; B) 3; C) It is impossible to say.
The answer is 3 (not "It is impossible to say").
This implies that you cannot get a result of 3.5
The implication of this is that Math.random() won't return .99999. I realise it's result is 0<=x<1.0. So is the result only to four decimal places (ie max value is 0.9999)?


Hi,
Math.random() results in double primitive type and you get result to approx. 12 decimal places but it will always be less than 1 so after adding to 2.50001 it will always be very close to 3 but never equal to 3, and Math.round() results in long primitive type so you get 3
I hope its clear
Jyotsna
 
Trevor Green
Ranch Hand
Posts: 44
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
If Math.random() returns a double to 12 decimal places, then 0.999999999999 is possible.
2.50001 + 0.99999999999 = 3.5000009999
This would round to 4. But the answer is B) 3.
Isn't it c) It is impossible to say, because, in this rarest of cases, it could also be 4, as well as 3?
 
anand raman
Ranch Hand
Posts: 66
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
i agree with you.
-Anand

[This message has been edited by anand raman (edited June 13, 2001).]
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic