/[MITgcm]/MITgcm/eesupp/src/different_multiple.F
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Contents of /MITgcm/eesupp/src/different_multiple.F

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Revision 1.5 - (show annotations) (download)
Fri Sep 21 03:54:34 2001 UTC (24 years, 1 month ago) by cnh
Branch: MAIN
CVS Tags: checkpoint46n_post, checkpoint51k_post, checkpoint47e_post, checkpoint52l_pre, checkpoint44e_post, hrcube4, hrcube5, checkpoint46l_post, checkpoint46g_pre, checkpoint47c_post, release1_p13_pre, checkpoint50c_post, checkpoint46f_post, checkpoint52d_pre, checkpoint48e_post, checkpoint50c_pre, checkpoint44f_post, checkpoint46b_post, checkpoint52j_pre, checkpoint43a-release1mods, checkpoint51o_pre, ecco_c50_e32, ecco_c50_e33, ecco_c50_e30, ecco_c50_e31, release1_p13, checkpoint51l_post, checkpoint48i_post, checkpoint46l_pre, checkpoint50d_pre, checkpoint52k_post, chkpt44d_post, checkpoint51, checkpoint50, checkpoint52, release1_p8, release1_p9, checkpoint50d_post, release1_p1, release1_p2, release1_p3, release1_p4, release1_p5, release1_p6, release1_p7, checkpoint52f_post, checkpoint50b_pre, checkpoint44e_pre, checkpoint51f_post, release1_b1, ecco_c51_e34d, ecco_c51_e34e, ecco_c51_e34f, ecco_c51_e34g, ecco_c51_e34a, ecco_c51_e34b, ecco_c51_e34c, checkpoint48b_post, checkpoint43, checkpoint51d_post, checkpoint48c_pre, checkpoint47d_pre, checkpoint51t_post, checkpoint51n_post, release1_chkpt44d_post, checkpoint52i_pre, hrcube_1, hrcube_2, hrcube_3, checkpoint51s_post, checkpoint47a_post, checkpoint48d_pre, checkpoint51j_post, checkpoint47i_post, checkpoint52e_pre, release1_p11, checkpoint52e_post, checkpoint51n_pre, checkpoint47d_post, icebear5, icebear4, icebear3, icebear2, checkpoint46d_pre, checkpoint48d_post, release1-branch_tutorials, checkpoint48f_post, checkpoint45d_post, checkpoint52b_pre, checkpoint46j_pre, ecco_c50_e28, checkpoint51l_pre, chkpt44a_post, checkpoint44h_pre, checkpoint48h_post, checkpoint51q_post, ecco_c50_e29, checkpoint51b_pre, checkpoint46a_post, checkpoint47g_post, checkpoint52b_post, checkpoint52c_post, checkpoint46j_post, checkpoint51h_pre, checkpoint46k_post, checkpoint46b_pre, chkpt44c_pre, checkpoint48a_post, checkpoint45a_post, checkpoint50f_post, checkpoint50a_post, checkpoint50f_pre, checkpoint52f_pre, ecco_c44_e19, ecco_c44_e18, ecco_c44_e17, ecco_c44_e16, release1_p12, release1_p10, release1_p16, release1_p17, release1_p14, release1_p15, checkpoint47j_post, ecco_c50_e33a, branch-exfmods-tag, checkpoint44g_post, branchpoint-genmake2, checkpoint46e_pre, checkpoint51r_post, checkpoint48c_post, checkpoint45b_post, checkpoint51i_post, release1-branch-end, release1_final_v1, checkpoint51b_post, checkpoint51c_post, checkpoint46c_pre, checkpoint46, checkpoint47b_post, checkpoint44b_post, ecco_c51_e34, checkpoint46h_pre, checkpoint52d_post, checkpoint46m_post, checkpoint46a_pre, checkpoint50g_post, checkpoint45c_post, ecco_ice2, ecco_ice1, checkpoint44h_post, checkpoint46g_post, release1_p12_pre, checkpoint52a_pre, ecco_c44_e22, checkpoint50h_post, checkpoint52i_post, checkpoint50e_pre, checkpoint50i_post, ecco_c44_e25, checkpoint51i_pre, checkpoint52h_pre, checkpoint52j_post, checkpoint47f_post, checkpoint50e_post, chkpt44a_pre, checkpoint46i_post, ecco_c44_e23, ecco_c44_e20, ecco_c44_e21, ecco_c44_e26, ecco_c44_e27, ecco_c44_e24, checkpoint46c_post, ecco-branch-mod1, ecco-branch-mod2, ecco-branch-mod3, ecco-branch-mod4, ecco-branch-mod5, branch-netcdf, checkpoint52l_post, checkpoint46e_post, release1_beta1, checkpoint51e_post, checkpoint44b_pre, checkpoint42, checkpoint41, checkpoint47, checkpoint44, checkpoint45, checkpoint48, checkpoint49, checkpoint46h_post, checkpoint51o_post, checkpoint51f_pre, chkpt44c_post, checkpoint48g_post, checkpoint47h_post, checkpoint52a_post, checkpoint44f_pre, checkpoint51g_post, ecco_c52_e35, checkpoint46d_post, checkpoint50b_post, release1-branch_branchpoint, checkpoint51m_post, checkpoint51a_post, checkpoint51p_post, checkpoint51u_post
Branch point for: c24_e25_ice, branch-exfmods-curt, release1_final, release1-branch, branch-genmake2, release1, branch-nonh, tg2-branch, ecco-branch, release1_50yr, netcdf-sm0, icebear, checkpoint51n_branch, release1_coupled
Changes since 1.4: +32 -16 lines 
Starting to bring comments up to date and format comments
for document extraction of "prototypes".
1 C $Header: /u/gcmpack/models/MITgcmUV/eesupp/src/different_multiple.F,v 1.4 2001/02/04 14:38:42 cnh Exp $
2 C $Name: $
3 #include "CPP_EEOPTIONS.h"
4
5 CBOP
6 C !ROUTINE: DIFFERENT_MULTIPLE
7
8 C !INTERFACE:
9 LOGICAL FUNCTION DIFFERENT_MULTIPLE( freq, val1, val2 )
10 IMPLICIT NONE
11
12 C !DESCRIPTION:
13 C *==========================================================*
14 C | LOGICAL FUNCTION DIFFERENT_MULTIPLE
15 C | o Checks two numbers multiple of a third number.
16 C *==========================================================*
17 C | This routine is used for diagnostic and other periodic
18 C | operations. It is very sensitive to arithmetic precision.
19 C | For IEEE conforming arithmetic it works well but for
20 C | cases where short cut arithmetic is used it may not work
21 C | as expected. To overcome this issue compile this routine
22 C | separately with no optimisation.
23 C *==========================================================*
24
25 C !INPUT PARAMETERS:
26 C == Routine arguments ==
27 C val1, val2 :: Two times that are checked
28 C freq :: Frequency by which times are divided.
29 _RL freq, val1, val2
30
31 C !LOCAL VARIABLES:
32 C == Local variables ==
33 C f :: Temp. for holding freq
34 C v1, v2, v3, v4 :: Temp. for holding time
35 C d1, d2, d3 :: Temp. for hold difference
36 C step :: Temp. for hold difference used as increment
37 _RL f, v1, v2, v3, v4, d1, d2, d3, step
38 CEOP
39
40 C o Do easy cases first.
41 DIFFERENT_MULTIPLE = .FALSE.
42
43 IF ( freq .NE. 0. ) THEN
44 IF ( ABS(val1-val2) .GT. freq ) THEN
45 DIFFERENT_MULTIPLE = .TRUE.
46 ELSE
47
48 C o This case is more complex because of round-off error
49 f = freq
50 v1 = val1
51 v2 = val2
52 step = v1-v2
53
54 C Test v1 to see if its a "closest multiple"
55 v3 = v1 + step
56 v4 = NINT(v1/f)*f
57 d1 = v1-v4
58 d2 = v2-v4
59 d3 = v3-v4
60 IF ( ABS(d1) .LE. ABS(d2) .AND. ABS(d1) .LE. ABS(d3) )
61 & DIFFERENT_MULTIPLE = .TRUE.
62
63 ENDIF ! |val1-val2| > freq
64 ENDIF ! freq != 0
65
66 END
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