JGonzalez
5386114d15
Seems things are a bit better. Still, more cases are needed and still not perfectly uniform...
94 lines
2 KiB
Fortran
94 lines
2 KiB
Fortran
MODULE moduleRandom
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!Interface for random number generator
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INTERFACE random
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MODULE PROCEDURE randomReal, randomRealAB, randomIntAB
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END INTERFACE random
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CONTAINS
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!Returns a Real random number between 0 and 1
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FUNCTION randomReal() RESULT(rnd)
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IMPLICIT NONE
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REAL(8):: rnd
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rnd = 0.D0
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CALL RANDOM_NUMBER(rnd)
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END FUNCTION randomReal
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!Returns a Real random number between a and b
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FUNCTION randomRealAB(a, b) RESULT(rnd)
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IMPLICIT NONE
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REAL(8), INTENT(in):: a, b
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REAL(8):: rnd
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REAL(8):: rnd01 !random real between 0 and 1
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rnd = 0.D0
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CALL RANDOM_NUMBER(rnd01)
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rnd = (b - a) * rnd01 + a
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END FUNCTION randomRealAB
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!Returns an Integer random numnber between a and b
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FUNCTION randomIntAB(a, b) RESULT(rnd)
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IMPLICIT NONE
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INTEGER, INTENT(in):: a, b
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INTEGER:: rnd
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REAL(8):: rnd01
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rnd = 0.D0
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CALL RANDOM_NUMBER(rnd01)
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rnd = INT(REAL(b - a) * rnd01) + 1
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END FUNCTION randomIntAB
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!Returns a random number in a Maxwellian distribution of mean 0 and width 1
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FUNCTION randomMaxwellian() RESULT(rnd)
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USE moduleConstParam, ONLY: PI
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IMPLICIT NONE
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REAL(8):: rnd
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REAL(8):: x, y
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rnd = 0.D0
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x = 0.D0
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DO WHILE (x == 0.D0)
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CALL RANDOM_NUMBER(x)
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END DO
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CALL RANDOM_NUMBER(y)
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rnd = DSQRT(-2.D0*DLOG(x))*DCOS(2.D0*PI*y)
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END FUNCTION randomMaxwellian
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!Returns a random number weighted with the cumWeight array
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FUNCTION randomWeighted(cumWeight, sumWeight) RESULT(rnd)
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IMPLICIT NONE
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REAL(8), INTENT(in):: cumWeight(1:)
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REAL(8), INTENT(in):: sumWeight
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REAL(8):: rnd0b
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INTEGER:: rnd, i
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rnd0b = random()
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i = 1
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DO
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IF (rnd0b <= cumWeight(i)/sumWeight) THEN
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rnd = i
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EXIT
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ELSE
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i = i +1
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END IF
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END DO
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! rnd = MINLOC(DABS(rnd0b - cumWeight), 1)
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END FUNCTION randomWeighted
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END MODULE moduleRandom
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