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| 5 | <title>grad.pro (SAXO Documentation Assistant)</title> |
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| 47 | <td width="10%"> |
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[168] | 48 | <a href="div.html"><img src="./../prev.gif" border="0" alt="Previous"></a></td> |
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[163] | 49 | <td width="80%" align="center" valign="center"> |
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[168] | 50 | <font size=-1><i>SAXO Documentation Assistant</i>: <a href="./../home.html">Overview</a></font></td> |
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[163] | 51 | <td width="10%" align="right"> |
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[168] | 52 | <a href=""><img src="./../next.gif" border="0" alt="Next"></a></td> |
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[163] | 53 | </tr> |
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| 54 | </table> |
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| 55 | |
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| 56 | |
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[168] | 57 | <h1><font size="-2">Computation/</font></h1> |
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[163] | 58 | <h2>grad.pro</h2> |
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| 59 | |
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| 60 | <dl> |
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| 61 | </dl> |
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| 62 | |
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| 63 | |
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[168] | 64 | compute the gradient of a variable |
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[163] | 65 | |
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| 66 | |
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| 67 | |
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| 68 | |
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| 69 | |
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| 70 | <a name="#_grad"></a> |
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| 71 | |
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| 72 | <h2>grad <font size="-1" color="#006633"> |
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[168] | 73 | Calculation |
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[163] | 74 | </font></h2> |
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| 75 | |
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| 76 | <p><font face="Courier"><i>result = </i>grad(<i><a href="#_grad_keyword_field">field</a>, <a href="#_grad_keyword_direc">direc</a></i>)</font></p> |
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[168] | 80 | <h3>Return value</h3> RES {type=2D, 3D or 4D array} |
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| 81 | the gradient of the input data (with the same size) |
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[163] | 82 | |
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| 83 | |
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| 84 | |
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| 85 | <h3>Parameters</h3> |
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| 86 | |
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| 87 | |
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| 88 | <a name="#_grad_keyword_field"></a> |
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| 89 | <h4>field |
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| 90 | |
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| 97 | |
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| 98 | </h4> |
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| 99 | |
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| 100 | |
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[168] | 101 | The field for which we want to compute the gradient. A 2D (xy), |
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| 102 | 3D (xyz or yt) or 4D (xyzt) array or a structure readable by litchamp |
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| 103 | and containing a 2D (xy), 3D (xyz or yt) or 4D (xyzt) array. |
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| 104 | note that the dimension of the arry must suit the domain dimension. |
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[163] | 105 | |
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| 106 | |
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| 107 | |
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| 108 | <a name="#_grad_keyword_direc"></a> |
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| 109 | <h4>direc |
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| 110 | |
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| 111 | |
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| 112 | |
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| 113 | |
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| 114 | |
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[168] | 115 | <font size="-1" color="#006633">type:</font> <font size="-1" color="#006633"><i>scalar string</i></font> |
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[163] | 116 | |
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| 117 | |
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| 118 | </h4> |
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| 119 | |
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| 120 | |
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[168] | 121 | the gradient direction: 'x', 'y', 'z' |
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[163] | 122 | |
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| 127 | |
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| 128 | <h3>Examples</h3> |
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[168] | 129 | IDL> @tst_initorca2 |
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| 130 | IDL> plt, grad({arr:gphit,g:'T'}, 'x') |
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| 131 | IDL> plt, grad({arr:gphit,g:'T'}, 'y') |
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[163] | 132 | |
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| 133 | <h3>Version history</h3> |
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| 134 | |
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| 135 | <h4>Version</h4> |
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[177] | 136 | $Id: grad.pro 168 2006-09-06 10:46:29Z pinsard $ |
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[163] | 137 | |
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| 138 | <h4>History</h4> |
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| 139 | Sebastien Masson (smasson@lodyc.jussieu.fr) |
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| 140 | |
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| 141 | |
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| 142 | |
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| 143 | <h3>Known issues</h3> |
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| 144 | |
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| 145 | |
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[168] | 146 | |
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[163] | 147 | <h4>Restrictions</h4> |
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[168] | 148 | - Works only for Arakawa C-grid. |
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| 149 | - When computing the gradient, the result is not on the same grid point |
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| 150 | than the input data. In consequence, we update, vargrid and the grid position |
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| 151 | parameters (firstx[tuvf], lastx[tuvf], nx[tuvf], firsty[tuvf], lasty[tuvf], |
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| 152 | ny[tuvf], firstz[tw], lastz[tw], nz[tw]). |
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| 153 | - points that cannot be computed (domain bondaries, coastline) are set to NaN |
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| 154 | - the common variable jpt is used to differ xyz (jpt=1) and xyt (jpt=1) cases. |
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[163] | 155 | |
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| 156 | |
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| 157 | <h3>Other attributes</h3> |
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| 158 | |
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| 159 | |
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| 160 | <h4>Uses routines</h4> |
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[168] | 161 | cm_4cal, cm_4data, cm_4mmesh |
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[163] | 162 | |
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[177] | 173 | <p><font color="gray" size="-3"> Produced by IDLdoc 2.0 on Wed Sep 13 16:32:08 2006.</font></p> |
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[163] | 174 | |
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| 175 | </body> |
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| 176 | </html> |
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