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# Random Number Generator Between 0 and 1?

## Random Number Generator Between 0 and 1?

(OP)
Hi Guys,
Just needed a bit of help writing a program that gives a number between 0 and 1.

I have so far written:

===============================
Program Main
Implicit None
Integer :: i, count, j=1

write(*,*) "how many times do you want to generate?"

call random_seed(1)
Do i=1,count
call random_number(j)
Write(*,*) "the random number is" j
End Do

End Program Main

===============================

So far the program keeps giving me huge numbers (positive and negative)

I only want numbers between 0 and 1. Any ideas please?

Many thanks
==========================

### RE: Random Number Generator Between 0 and 1?

How can you expect, that j will be between 0 and 1 when you declared it as an integer?
If you try to compile your program with gfortran you will get this error:

$rnd how many times do you want to generate? 5 the random number is 0.99755955 the random number is 0.56682467 the random number is 0.96591532 the random number is 0.74792767 the random number is 0.36739087 ### RE: Random Number Generator Between 0 and 1? (OP) Thanks for that. ofcourse, i overlooked the real issue :p Just a note though, everytime I run the program, it keeps generating the same sequence of random numbers. So in fact, I'm not acutally getting a random sequence each time I run the program. Any ways to solve this? By the way, are there any good compilers available? I'm using PLATO by silverfrost, but when i compile the program and run it, all integers seem to have a BIG padding before them (a huge space for no reason)? Thanks ### RE: Random Number Generator Between 0 and 1? Instead of #### CODE call random_seed(seed) try to use #### CODE call init_random_seed() The subroutine is defined here: http://gcc.gnu.org/onlinedocs/gfortran/RANDOM_005fSEED.html#RANDOM_005fSEED I tried it in gfortran and it works - it generates everytime different random numbers: #### CODE$ gfortran rnd.f95 -o rnd

$rnd how many times do you want to generate? 3 the random number is 4.18258309E-02 the random number is 0.95481700 the random number is 0.38921034$ rnd
how many times do you want to generate?
3
the random number is  0.95889604
the random number is  0.78550929
the random number is  0.70096797

$rnd how many times do you want to generate? 3 the random number is 2.19990611E-02 the random number is 0.50352961 the random number is 0.90276980 But with g95 it doesn't work - it generates everytime same numbers: #### CODE$ g95 rnd.f95 -o rnd

$rnd how many times do you want to generate? 3 the random number is 0.8157187 the random number is 0.9665488 the random number is 0.8606074$ rnd
how many times do you want to generate?
3
the random number is 0.8157187
the random number is 0.9665488
the random number is 0.8606074
I don't know why...

#### Quote (androidmelt):

By the way, are there any good compilers available?
As I mentioned I'm using g95, gfortran and g77. All are free available.

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