simulate_uniform - fabiankindermann/ce-fortran GitHub Wiki

subroutine simulate_uniform(x, a, b, fixed)

Description:

Simulates independent draws from a random variable following a uniform distribution on the interval .

real*8 :: x or real*8 :: x(:)
The subroutine stores the realizations of the draws from the random variable in the scalar or one-dimensional array x. If x is a scalar, the subroutine only draws one realization. If x is a one-dimensional array, the subroutine fills up all the array elements with independent draws from the random variable.

real*8 :: a
The left endpoint of the interval on which the distribution exists. If not present, the subroutine uses a = 0.
real*8 :: b
The right endpoint of the interval on which the distribution exists. If not present, the subroutine uses b = 1. Note that needs to hold, otherwise the subroutine throws an error message.
logical :: fixed
If a logical variable fixed is passed to the subroutine that takes the value .true., the subroutine uses a fixed random seed. As a result, the sequence of random numbers drawn by the subroutine will always be the same every time your program is restarted. If fixed is not present or takes a value of .false., then the random seed is initialized at some arbitrary value that depends on the time and date at which you started your program. Hence, the series of random numbers drawn by this subroutine will be different every time your program is restarted.

Parts of this routine were copied and adapted from:
- The GNU gfortran compiler documentation for the initialization of the seed of the random number generator.
For further reading refer to:
- Toral, R. & Colet, P. (2014). Stochastic Numerical Methods: An Introduction for Students and Scientists. Weinheim: Wiley.
This routine is used in the following programs:
- prog02_16.f90
- prog04_03.f90
- prog04_08.f90