problem with rand()

[pereges]

I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only zeros as
output.
#include <stdio.h>
#include <stdlib.h>

int main(void)
{

int i;
int a;
for(i=0;i<10;i+ +)
{
a =((double)rand( ))/(RAND_MAX+1) ;
printf("%f", a);
}
return 0;
}

[Richard Heathfield]

Re: problem with rand()

pereges said:

I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only zeros as
output.
#include <stdio.h>
#include <stdlib.h>
>
int main(void)
{
>
int i;
int a;

You didn't mean int a, but double a

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
int i = 0;
while(i++ < 10)
{
double a = rand() / (RAND_MAX + 1.0);
printf("%f\n", a);
}
return 0;
}

Now see if you can work out why you get the same results on every run. (The
FAQ has something to say about this.)

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[Joachim Schmitz]

Re: problem with rand()

pereges wrote:

I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only zeros as
output.
#include <stdio.h>
#include <stdlib.h>
>
int main(void)
{
>
int i;
int a;

double a;

for(i=0;i<10;i+ +)
{
a =((double)rand( ))/(RAND_MAX+1) ;
printf("%f", a);
}
return 0;
}

Bye, Jojo

[Lew Pitcher]

Re: problem with rand()

pereges wrote:

I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only zeros as
output.
#include <stdio.h>
#include <stdlib.h>
>
int main(void)
{
>
int i;
int a;

NB: ---^

for(i=0;i<10;i+ +)
{
a =((double)rand( ))/(RAND_MAX+1) ;

Questions for the student:
1) What value of rand() will cause a to equal 1?
2) How likely would it be for rand() to return the value that would
cause a to compute out to 1?
3) What will a be set to for all other values returned by rand()?

printf("%f", a);
}
return 0;
}

--
Lew Pitcher

Master Codewright & JOAT-in-training | Registered Linux User #112576
http://pitcher.digitalfreehold.ca/ | GPG public key available by request
---------- Slackware - Because I know what I'm doing. ------

[pereges]

Re: problem with rand()

On Apr 15, 10:18 pm, Richard Heathfield <r...@see.sig.i nvalidwrote:

pereges said:
>

I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only zeros as
output.
#include <stdio.h>
#include <stdlib.h>

>

int main(void)
{

>

int i;
int a;

>
You didn't mean int a, but double a
>
#include <stdio.h>
#include <stdlib.h>
>
int main(void)
{
int i = 0;
while(i++ < 10)
{
double a = rand() / (RAND_MAX + 1.0);
printf("%f\n", a);
}
return 0;
>
}
>
Now see if you can work out why you get the same results on every run. (The
FAQ has something to say about this.)
>
--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[CBFalconer]

Re: problem with rand()

pereges wrote:

>
I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only
zeros as output.
>
#include <stdio.h>
#include <stdlib.h>
>
int main(void) {
int i;
int a;
for(i=0;i<10;i+ +) {
a =((double)rand( ))/(RAND_MAX+1) ;
printf("%f", a);
}
return 0;
}

Putting in proper use of spaces and proper variable typing (note
the absence of casts) results in:

#include <stdio.h>
#include <stdlib.h>

int main(void) {
int i;
double a;

for (i = 0; i < 10; i++) {
a = rand() / ((RAND_MAX) + 1.0) ;
printf("%f\n", a);
}
return 0;
}

Also note the use of 1.0 in place of 1. This can never generate
output values of 1.0.

--
[mail]: Chuck F (cbfalconer at maineline dot net)
[page]: <http://cbfalconer.home .att.net>
Try the download section.

** Posted from http://www.teranews.com **

[Jack.Thomson.v3@gmail.com]

Re: problem with rand()

On Apr 15, 10:12 pm, pereges <Brol...@gmail. comwrote:

I wrote the following program to generate a seuence of uniformly
distributed random points between 0 and 1. It is giving only zeros as
output.
#include <stdio.h>
#include <stdlib.h>
>
int main(void)
{
>
int i;
int a;
for(i=0;i<10;i+ +)
{
a =((double)rand( ))/(RAND_MAX+1) ;
printf("%f", a);
}
return 0;}

#include <stdio.h>
#include <stdlib.h>

int main(void)
{

int i;
double a; // Here is the modification

for(i=0;i<10;i+ +)
{
a =((double)rand( ))/(RAND_MAX+1) ;
printf("%f", a);
}
return 0;
}


~Jack

http://programmingsite.googlepages.com