[1677] | 1 | FUNCTION sqdis (px1, py1, px2, py2) |
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| 2 | C**** |
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| 3 | C ****************************** |
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| 4 | C * OASIS FUNCTION - LEVEL T * |
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| 5 | C * -------------- ------- * |
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| 6 | C ****************************** |
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| 7 | C |
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| 8 | C**** *sqdis* - Arithmetic function |
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| 9 | C |
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| 10 | C Purpose: |
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| 11 | C ------- |
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| 12 | C Calculate the distance squared between 2 points on a spheric grid |
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| 13 | C |
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| 14 | C** Interface: |
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| 15 | C --------- |
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| 16 | C *zs =* *sqdis (px1, py1, px2, py2)* |
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| 17 | C |
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| 18 | C Input: |
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| 19 | C ----- |
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| 20 | C px1 : longitude of first point |
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| 21 | C py1 : latitude of first point |
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| 22 | C px2 : longitude of second point |
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| 23 | C py2 : latitude of second point |
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| 24 | C |
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| 25 | C NB: the coordinates must be in degrees |
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| 26 | C |
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| 27 | C Output: |
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| 28 | C ------ |
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| 29 | C None |
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| 30 | C |
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| 31 | C Workspace: |
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| 32 | C --------- |
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| 33 | C None |
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| 34 | C |
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| 35 | C Externals: |
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| 36 | C --------- |
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| 37 | C None |
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| 38 | C |
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| 39 | C Reference: |
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| 40 | C --------- |
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| 41 | C See OASIS manual (1995) |
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| 42 | C |
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| 43 | C History: |
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| 44 | C ------- |
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| 45 | C Version Programmer Date Description |
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| 46 | C ------- ---------- ---- ----------- |
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| 47 | C 2.0 L. Terray 95/09/01 created |
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| 48 | C |
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| 49 | C %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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| 50 | C |
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| 51 | C* ---------------------------- Include files --------------------------- |
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| 52 | C |
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| 53 | USE mod_kinds_oasis |
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| 54 | USE mod_unit |
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| 55 | C |
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| 56 | C* ---------------------------- Function declarations ------------------- |
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| 57 | C |
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| 58 | REAL (kind=ip_realwp_p) sqdis, fast |
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| 59 | fast(x,y,z) = cos(x)*cos(y)*z + sin(x)*sin(y) |
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| 60 | C |
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| 61 | C* ---------------------------- Poema verses ---------------------------- |
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| 62 | C |
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| 63 | C %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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| 64 | C |
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| 65 | C* 1. Calculate distance |
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| 66 | C ------------------ |
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| 67 | C |
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| 68 | C* Degree to radians --> zcon = 2. pi / 360. |
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| 69 | C |
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| 70 | zconv = 1.74532925199432957692e-2 |
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| 71 | zfi1 = px1 * zconv |
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| 72 | zth1 = py1 * zconv |
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| 73 | zfi2 = px2 * zconv |
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| 74 | zth2 = py2 * zconv |
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| 75 | C |
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| 76 | C* Scalar product |
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| 77 | C |
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| 78 | ztp1 = fast(zfi1, zfi2, 1.) |
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| 79 | zsca = fast(zth1, zth2, ztp1) |
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| 80 | C |
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| 81 | C* Angular distance |
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| 82 | C |
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| 83 | IF (zsca .GT. 1.) THEN |
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| 84 | WRITE(UNIT = nulan,FMT = *) |
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| 85 | $ ' Scalar product is greater than 1 ' |
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| 86 | WRITE(UNIT = nulan,FMT = *) |
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| 87 | $ ' for point 1 --> longitude = ', px1 |
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| 88 | WRITE(UNIT = nulan,FMT = *) |
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| 89 | $ ' --> latitude = ', py1 |
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| 90 | WRITE(UNIT = nulan,FMT = *) |
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| 91 | $ ' and point 2 --> longitude = ', px2 |
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| 92 | WRITE(UNIT = nulan,FMT = *) |
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| 93 | $ ' --> latitude = ', py2 |
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| 94 | WRITE(UNIT = nulan,FMT = *) |
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| 95 | $ ' Scalar product zsca = ', zsca |
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| 96 | zsca =1. |
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| 97 | ENDIF |
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| 98 | IF (zsca .LT. -1.) THEN |
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| 99 | WRITE(UNIT = nulan,FMT = *) |
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| 100 | $ ' Scalar product is less than -1 ' |
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| 101 | WRITE(UNIT = nulan,FMT = *) |
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| 102 | $ ' for point 1 --> longitude = ', px1 |
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| 103 | WRITE(UNIT = nulan,FMT = *) |
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| 104 | $ ' --> latitude = ', py1 |
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| 105 | WRITE(UNIT = nulan,FMT = *) |
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| 106 | $ ' and point 2 --> longitude = ', px2 |
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| 107 | WRITE(UNIT = nulan,FMT = *) |
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| 108 | $ ' --> latitude = ', py2 |
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| 109 | WRITE(UNIT = nulan,FMT = *) |
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| 110 | $ ' Scalar product zsca = ', zsca |
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| 111 | zsca = -1. |
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| 112 | ENDIF |
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| 113 | C |
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| 114 | C* Get the distance |
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| 115 | C |
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| 116 | zalp = acos(zsca) |
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| 117 | sqdis = zalp * zalp |
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| 118 | C |
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| 119 | C* End of function |
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| 120 | C |
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| 121 | RETURN |
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| 122 | END |
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