On 14/08/2017 2:18 PM, Huzefa Khalil wrote:
Hi Martin,
The corrected function would be
RANDU <- function(num) { return ((65539*num)%%(2^31)) }
You forgot the brackets for the return function.
Hence, what was returned was always (65539 * num)
Yes, this is one disadvantage of having a return function rather than
reserved word.
It is also an argument for avoiding the use of return(); Martin's
function could be written as
RANDU <- function(num) { (65539*num)%%(2^31) }
or even
RANDU <- function(num) (65539*num)%%(2^31)
since the braces aren't needed when a function body has only a single
statement.
Duncan Murdoch
On Mon, Aug 14, 2017 at 12:49 PM, Martin Møller Skarbiniks Pedersen
<traxpla...@gmail.com> wrote:
Dear all,
I am trying to learn functions in R and 3D plotting so I decided to try
to plot
the famous bad PRNG Randu from IBM(1).
However something is not correct in the function I have created.
First I define the function RANDU like this:
RANDU <- function(num) { return (65539*num)%%(2^31) }
and test that it works for a seed of 1:
RANDU(1)
[1] 65539
but if I want the next value in the sequence I get this number.
(65539*65539)%%(2^31)
[1] 393225
However using the RANDU function twice doesn't give the same result as
above.
RANDU(RANDU(1))
[1] 4295360521
I expect these two values to be the same but that is not the case.
393225 should be the correct.
I guess it might be something with local vs. global environment ?!
Please advise and thanks.
Regards
Martin M. S. Pedersen
(1) https://en.wikipedia.org/wiki/RANDU
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
