[1885] | 1 | MODULE ran_num |
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| 2 | !!====================================================================== |
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| 3 | !! *** MODULE ran_num *** |
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| 4 | !! NEMOVAR: Random number routines |
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| 5 | !!====================================================================== |
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| 6 | !!---------------------------------------------------------------------- |
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| 7 | !! gaustb : returns a gaussian randum number with mean and std. |
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| 8 | !! gaustb_2d : returns a gaussian randum number with mean and std for a |
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| 9 | !! given horizontal grid point |
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| 10 | !!---------------------------------------------------------------------- |
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| 11 | !! * Modules used |
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| 12 | USE par_kind ! Kind variables |
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| 13 | USE dom_oce ! Domain variables |
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| 14 | USE in_out_manager ! I/O stuff |
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| 15 | |
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| 16 | IMPLICIT NONE |
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| 17 | |
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| 18 | !! * Routine accessibility |
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| 19 | |
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| 20 | PRIVATE |
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| 21 | |
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| 22 | PUBLIC & |
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| 23 | & gaustb, & |
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| 24 | & gaustb_2d |
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| 25 | |
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| 26 | CONTAINS |
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| 27 | |
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| 28 | FUNCTION gaustb( kseed, pamp, pmean ) |
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| 29 | !!---------------------------------------------------------------------- |
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| 30 | !! *** ROUTINE gaustb *** |
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| 31 | !! |
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| 32 | !! ** Purpose : Returns a gaussian randum number with mean and std. |
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| 33 | !! |
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| 34 | !! ** Method : Generate Gaussian random variables. |
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| 35 | !! The standard deviation and mean of the variables are |
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| 36 | !! specified by the variables pamp and pmean. |
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| 37 | !! |
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| 38 | !! ** Action : |
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| 39 | !! |
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| 40 | !! History : |
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| 41 | !! ! 07-07 (K. Mogensen) Original code based on gaustb.F |
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| 42 | !!---------------------------------------------------------------------- |
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| 43 | !! * Function return |
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| 44 | REAL(wp) :: & |
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| 45 | & gaustb |
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| 46 | !! * Arguments |
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| 47 | INTEGER, INTENT(INOUT) :: & |
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| 48 | & kseed ! Seed |
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| 49 | REAL(wp), INTENT(IN) :: & |
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| 50 | & pamp, & ! Amplitude |
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| 51 | & pmean ! Mean value |
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| 52 | !! * Local declarations |
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| 53 | |
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| 54 | gaustb = pamp * gausva( kseed ) + pmean |
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| 55 | |
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| 56 | END FUNCTION gaustb |
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| 57 | |
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| 58 | |
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| 59 | FUNCTION gausva( kdum ) |
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| 60 | !!---------------------------------------------------------------------- |
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| 61 | !! *** ROUTINE gausva *** |
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| 62 | !! |
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| 63 | !! ** Purpose : Returns a normally distributed deviate with 0 mean |
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| 64 | !! and unit variance using the unifva(kdum) as the |
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| 65 | !! source of uniform deviates. |
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| 66 | !! |
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| 67 | !! ** Method : |
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| 68 | !! |
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| 69 | !! ** Action : |
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| 70 | !! |
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| 71 | !! History : |
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| 72 | !! ! 07-07 (K. Mogensen) Original code based on gaustb.F |
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| 73 | !!---------------------------------------------------------------------- |
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| 74 | !! * Function return |
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| 75 | REAL(wp) :: & |
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| 76 | & gausva |
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| 77 | !! * Arguments |
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| 78 | INTEGER, INTENT(INOUT) :: & |
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| 79 | & kdum ! Seed |
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| 80 | !! * Local declarations |
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| 81 | REAL(wp), SAVE :: & |
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| 82 | & gset |
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| 83 | INTEGER, SAVE :: & |
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| 84 | & niset = 0 |
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| 85 | REAL(wp) :: & |
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| 86 | & zfac, & |
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| 87 | & zrsq, & |
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| 88 | & zv1, & |
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| 89 | & zv2 |
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| 90 | |
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| 91 | ! Begin main |
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| 92 | |
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| 93 | IF ( niset == 0 ) THEN |
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| 94 | |
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| 95 | zv1 = 2.0_wp * psrandom( kdum ) - 1.0_wp |
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| 96 | zv2 = 2.0_wp * psrandom( kdum ) - 1.0_wp |
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| 97 | zrsq = zv1**2 + zv2**2 |
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| 98 | |
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| 99 | DO WHILE ( ( zrsq >= 1.0_wp ) .OR. ( zrsq == 0.0_wp ) ) |
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| 100 | |
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| 101 | zv1 = 2.0_wp * psrandom( kdum ) - 1.0_wp |
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| 102 | zv2 = 2.0_wp * psrandom( kdum ) - 1.0_wp |
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| 103 | zrsq = zv1**2 + zv2**2 |
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| 104 | |
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| 105 | END DO |
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| 106 | |
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| 107 | zfac = SQRT( -2.0_wp * LOG( zrsq ) / zrsq ) |
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| 108 | gset = zv1 * zfac |
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| 109 | gausva = zv2 * zfac |
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| 110 | niset = 1 |
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| 111 | |
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| 112 | ELSE |
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| 113 | |
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| 114 | gausva = gset |
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| 115 | niset = 0 |
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| 116 | |
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| 117 | ENDIF |
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| 118 | |
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| 119 | END FUNCTION gausva |
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| 120 | |
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| 121 | FUNCTION psrandom( kdum ) |
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| 122 | !!---------------------------------------------------------------------- |
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| 123 | !! *** ROUTINE psrandom *** |
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| 124 | !! |
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| 125 | !! ** Purpose : Pseudo-Random number generator. |
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| 126 | !! |
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| 127 | !! ** Method : Returns a pseudo-random number from a uniform distribution |
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| 128 | !! between 0 and 1 |
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| 129 | !! Call with kdum a negative integer to initialize. |
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| 130 | !! Thereafter, do not alter kdum between successive deviates |
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| 131 | !! in sequence. |
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| 132 | !! |
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| 133 | !! ** Action : |
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| 134 | !! |
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| 135 | !! History : |
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| 136 | !! ! 10-02 (F. Vigilant) Original code |
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| 137 | !!---------------------------------------------------------------------- |
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| 138 | !! * Function return |
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| 139 | REAL(wp) :: & |
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| 140 | & psrandom |
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| 141 | !! * Arguments |
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| 142 | INTEGER, INTENT(INOUT) :: & |
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| 143 | & kdum ! Seed |
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| 144 | LOGICAL, SAVE :: & |
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| 145 | & llinit = .FALSE. |
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| 146 | |
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| 147 | ! Initialization |
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| 148 | IF ( .NOT. llinit ) THEN |
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| 149 | |
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| 150 | CALL srand( kdum ) |
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| 151 | llinit = .TRUE. |
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| 152 | |
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| 153 | ENDIF |
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| 154 | |
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| 155 | CALL rand(psrandom) |
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| 156 | |
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| 157 | END FUNCTION psrandom |
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| 158 | |
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| 159 | |
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| 160 | FUNCTION gaustb_2d( ki, kj, kseed, pamp, pmean ) |
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| 161 | !!---------------------------------------------------------------------- |
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| 162 | !! *** ROUTINE gaustb_2d *** |
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| 163 | !! |
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| 164 | !! ** Purpose : Returns a Gaussian randum number with mean and std |
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| 165 | !! for a given horizontal grid point. |
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| 166 | !! |
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| 167 | !! ** Method : Generate Gaussian random variables. |
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| 168 | !! The standard deviation and mean of the variables are |
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| 169 | !! specified by the variables pamp and pmean. |
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| 170 | !! |
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| 171 | !! ** Action : |
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| 172 | !! |
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| 173 | !! History : |
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| 174 | !! ! 07-07 (K. Mogensen) Original code based on gaustb.F |
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| 175 | !!---------------------------------------------------------------------- |
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| 176 | !! * Function return |
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| 177 | REAL(wp) :: & |
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| 178 | & gaustb_2d |
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| 179 | !! * Arguments |
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| 180 | INTEGER, INTENT(IN) :: & |
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| 181 | & ki, & ! Indices in seed array |
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| 182 | & kj |
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| 183 | INTEGER, INTENT(INOUT), DIMENSION(jpi,jpj) :: & |
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| 184 | & kseed ! Seed |
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| 185 | REAL(wp), INTENT(IN) :: & |
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| 186 | & pamp, & ! Amplitude |
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| 187 | & pmean ! Mean value |
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| 188 | !! * Local declarations |
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| 189 | |
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| 190 | gaustb_2d = pamp * gausva_2d( ki, kj, kseed ) + pmean |
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| 191 | |
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| 192 | END FUNCTION gaustb_2d |
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| 193 | |
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| 194 | FUNCTION gausva_2d( ki, kj, kdum ) |
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| 195 | !!---------------------------------------------------------------------- |
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| 196 | !! *** ROUTINE gausva_2d *** |
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| 197 | !! |
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| 198 | !! ** Purpose : Returns a normally distributed deviate with 0 mean |
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| 199 | !! and unit variance. |
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| 200 | !! |
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| 201 | !! ** Method : |
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| 202 | !! |
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| 203 | !! ** Action : |
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| 204 | !! |
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| 205 | !! History : |
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| 206 | !! ! 07-07 (K. Mogensen) Original code based on gaustb.F |
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| 207 | !!---------------------------------------------------------------------- |
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| 208 | !! * Function return |
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| 209 | REAL(wp) :: & |
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| 210 | & gausva_2d |
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| 211 | !! * Arguments |
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| 212 | INTEGER, INTENT(IN) :: & |
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| 213 | & ki, & ! Indices in seed array |
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| 214 | & kj |
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| 215 | INTEGER, INTENT(INOUT), DIMENSION(jpi,jpj) :: & |
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| 216 | & kdum ! Seed |
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| 217 | !! * Local declarations |
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| 218 | REAL(wp), SAVE, DIMENSION(jpi,jpj) :: & |
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| 219 | & gset |
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| 220 | INTEGER, SAVE, DIMENSION(jpi,jpj) :: & |
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| 221 | & niset |
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| 222 | LOGICAL, SAVE :: & |
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| 223 | & llinit = .FALSE. |
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| 224 | REAL(wp) :: & |
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| 225 | & zfac, & |
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| 226 | & zrsq, & |
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| 227 | & zv1, & |
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| 228 | & zv2 |
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| 229 | |
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| 230 | ! Initialization |
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| 231 | |
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| 232 | IF ( .NOT. llinit ) THEN |
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| 233 | |
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| 234 | niset(:,:) = 0 |
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| 235 | llinit = .TRUE. |
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| 236 | |
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| 237 | ENDIF |
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| 238 | |
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| 239 | ! Begin main |
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| 240 | |
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| 241 | IF ( niset(ki,kj) == 0 ) THEN |
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| 242 | |
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| 243 | zv1 = 2.0_wp * psrandom_2d( ki, kj, kdum ) - 1.0_wp |
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| 244 | zv2 = 2.0_wp * psrandom_2d( ki, kj, kdum ) - 1.0_wp |
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| 245 | zrsq = zv1**2 + zv2**2 |
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| 246 | |
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| 247 | DO WHILE ( ( zrsq >= 1.0_wp ) .OR. ( zrsq == 0.0_wp ) ) |
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| 248 | |
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| 249 | zv1 = 2.0_wp * psrandom_2d( ki, kj, kdum ) - 1.0_wp |
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| 250 | zv2 = 2.0_wp * psrandom_2d( ki, kj, kdum ) - 1.0_wp |
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| 251 | zrsq = zv1**2 + zv2**2 |
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| 252 | |
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| 253 | END DO |
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| 254 | |
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| 255 | zfac = SQRT( -2.0_wp * LOG( zrsq ) / zrsq ) |
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| 256 | gset(ki,kj) = zv1 * zfac |
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| 257 | gausva_2d = zv2 * zfac |
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| 258 | niset(ki,kj) = 1 |
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| 259 | |
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| 260 | ELSE |
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| 261 | |
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| 262 | gausva_2d = gset(ki,kj) |
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| 263 | niset(ki,kj) = 0 |
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| 264 | |
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| 265 | ENDIF |
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| 266 | |
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| 267 | END FUNCTION gausva_2d |
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| 268 | |
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| 269 | FUNCTION psrandom_2d( ki, kj, kdum ) |
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| 270 | !!---------------------------------------------------------------------- |
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| 271 | !! *** ROUTINE psrandom_2d *** |
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| 272 | !! |
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| 273 | !! ** Purpose : Random number generator. |
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| 274 | !! |
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| 275 | !! ** Method : Returns a pseudo-random number from a uniform distribution |
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| 276 | !! between 0 and 1 |
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| 277 | !! Call with kdum a negative integer to initialize. |
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| 278 | !! Thereafter, do not alter kdum between successive deviates |
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| 279 | !! in sequence. |
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| 280 | !! |
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| 281 | !! ** Action : |
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| 282 | !! |
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| 283 | !! History : |
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| 284 | !! ! 10-02 (F. Vigilant) Original code |
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| 285 | !!---------------------------------------------------------------------- |
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| 286 | !! * Function return |
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| 287 | REAL(wp) :: & |
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| 288 | & psrandom_2d |
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| 289 | !! * Arguments |
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| 290 | INTEGER, INTENT(IN) :: & |
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| 291 | & ki, & ! Indices in seed array |
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| 292 | & kj |
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| 293 | INTEGER, INTENT(INOUT), DIMENSION(jpi,jpj) :: & |
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| 294 | & kdum ! Seed |
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| 295 | LOGICAL, SAVE :: & |
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| 296 | & llinit = .FALSE. |
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| 297 | |
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| 298 | ! Initialization |
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| 299 | IF ( .NOT. llinit ) THEN |
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| 300 | |
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| 301 | CALL srand( kdum( ki,kj ) ) |
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| 302 | llinit = .TRUE. |
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| 303 | |
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| 304 | ENDIF |
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| 305 | |
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| 306 | CALL rand(psrandom_2d) |
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| 307 | |
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| 308 | END FUNCTION psrandom_2d |
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| 309 | |
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| 310 | END MODULE ran_num |
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