| 1 | |
|---|
| 2 | |
|---|
| 3 | <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
|---|
| 4 | <head> |
|---|
| 5 | <title>grad.pro (SAXO Documentation Assistant)</title> |
|---|
| 6 | </head> |
|---|
| 7 | |
|---|
| 8 | <body text="#000000" bgcolor="#FFFFFF"> |
|---|
| 9 | |
|---|
| 10 | |
|---|
| 11 | <!-- Navbar template takes a structure with the following fields: |
|---|
| 12 | overview_href : |
|---|
| 13 | overview_selected : |
|---|
| 14 | dir_overview_href : |
|---|
| 15 | dir_overview_selected : |
|---|
| 16 | categories_href : |
|---|
| 17 | categories_selected : |
|---|
| 18 | index_href : |
|---|
| 19 | index_selected : |
|---|
| 20 | search_href : |
|---|
| 21 | search_selected : |
|---|
| 22 | file_selected : |
|---|
| 23 | source_href : |
|---|
| 24 | source_selected : |
|---|
| 25 | help_href : |
|---|
| 26 | help_selected : |
|---|
| 27 | etc_selected : |
|---|
| 28 | |
|---|
| 29 | prev_file_href : |
|---|
| 30 | next_file_href : |
|---|
| 31 | |
|---|
| 32 | view_single_page_href : |
|---|
| 33 | view_frames_href : |
|---|
| 34 | |
|---|
| 35 | summary_fields_href : |
|---|
| 36 | summary_routine_href : |
|---|
| 37 | details_routine_href : |
|---|
| 38 | |
|---|
| 39 | title : |
|---|
| 40 | subtitle : |
|---|
| 41 | user : |
|---|
| 42 | --> |
|---|
| 43 | |
|---|
| 44 | |
|---|
| 45 | <table border="0" cellpadding="0" cellspacing="0" width="98%" bgcolor="#F0F0FF" valign="bottom"> |
|---|
| 46 | <tr> |
|---|
| 47 | <td width="10%"> |
|---|
| 48 | <a href="div.html"><img src="./../prev.gif" border="0" alt="Previous"></a></td> |
|---|
| 49 | <td width="80%" align="center" valign="center"> |
|---|
| 50 | <font size=-1><i>SAXO Documentation Assistant</i>: <a href="./../home.html">Overview</a></font></td> |
|---|
| 51 | <td width="10%" align="right"> |
|---|
| 52 | <a href=""><img src="./../next.gif" border="0" alt="Next"></a></td> |
|---|
| 53 | </tr> |
|---|
| 54 | </table> |
|---|
| 55 | |
|---|
| 56 | |
|---|
| 57 | <h1><font size="-2">Computation/</font></h1> |
|---|
| 58 | <h2>grad.pro</h2> |
|---|
| 59 | |
|---|
| 60 | <dl> |
|---|
| 61 | </dl> |
|---|
| 62 | |
|---|
| 63 | |
|---|
| 64 | compute the gradient of a variable |
|---|
| 65 | |
|---|
| 66 | |
|---|
| 67 | |
|---|
| 68 | |
|---|
| 69 | |
|---|
| 70 | <a name="#_grad"></a> |
|---|
| 71 | |
|---|
| 72 | <h2>grad <font size="-1" color="#006633"> |
|---|
| 73 | Calculation |
|---|
| 74 | </font></h2> |
|---|
| 75 | |
|---|
| 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> |
|---|
| 77 | |
|---|
| 78 | |
|---|
| 79 | |
|---|
| 80 | <h3>Return value</h3> RES {type=2D, 3D or 4D array} |
|---|
| 81 | the gradient of the input data (with the same size) |
|---|
| 82 | |
|---|
| 83 | |
|---|
| 84 | |
|---|
| 85 | <h3>Parameters</h3> |
|---|
| 86 | |
|---|
| 87 | |
|---|
| 88 | <a name="#_grad_keyword_field"></a> |
|---|
| 89 | <h4>field |
|---|
| 90 | |
|---|
| 91 | |
|---|
| 92 | |
|---|
| 93 | |
|---|
| 94 | |
|---|
| 95 | |
|---|
| 96 | |
|---|
| 97 | |
|---|
| 98 | </h4> |
|---|
| 99 | |
|---|
| 100 | |
|---|
| 101 | The field for which we want to compute the gradient. A 2D (xy), |
|---|
| 102 | 3D (xyz or yt) or 4D (xyzt) array or a structure readable by litchamp |
|---|
| 103 | and containing a 2D (xy), 3D (xyz or yt) or 4D (xyzt) array. |
|---|
| 104 | note that the dimension of the arry must suit the domain dimension. |
|---|
| 105 | |
|---|
| 106 | |
|---|
| 107 | |
|---|
| 108 | <a name="#_grad_keyword_direc"></a> |
|---|
| 109 | <h4>direc |
|---|
| 110 | |
|---|
| 111 | |
|---|
| 112 | |
|---|
| 113 | |
|---|
| 114 | |
|---|
| 115 | <font size="-1" color="#006633">type:</font> <font size="-1" color="#006633"><i>scalar string</i></font> |
|---|
| 116 | |
|---|
| 117 | |
|---|
| 118 | </h4> |
|---|
| 119 | |
|---|
| 120 | |
|---|
| 121 | the gradient direction: 'x', 'y', 'z' |
|---|
| 122 | |
|---|
| 123 | |
|---|
| 124 | |
|---|
| 125 | |
|---|
| 126 | |
|---|
| 127 | |
|---|
| 128 | <h3>Examples</h3> |
|---|
| 129 | IDL> @tst_initorca2 |
|---|
| 130 | IDL> plt, grad({arr:gphit,g:'T'}, 'x') |
|---|
| 131 | IDL> plt, grad({arr:gphit,g:'T'}, 'y') |
|---|
| 132 | |
|---|
| 133 | <h3>Version history</h3> |
|---|
| 134 | |
|---|
| 135 | <h4>Version</h4> |
|---|
| 136 | $Id: grad.pro 168 2006-09-06 10:46:29Z pinsard $ |
|---|
| 137 | |
|---|
| 138 | <h4>History</h4> |
|---|
| 139 | Sebastien Masson (smasson@lodyc.jussieu.fr) |
|---|
| 140 | |
|---|
| 141 | |
|---|
| 142 | |
|---|
| 143 | <h3>Known issues</h3> |
|---|
| 144 | |
|---|
| 145 | |
|---|
| 146 | |
|---|
| 147 | <h4>Restrictions</h4> |
|---|
| 148 | - Works only for Arakawa C-grid. |
|---|
| 149 | - When computing the gradient, the result is not on the same grid point |
|---|
| 150 | than the input data. In consequence, we update, vargrid and the grid position |
|---|
| 151 | parameters (firstx[tuvf], lastx[tuvf], nx[tuvf], firsty[tuvf], lasty[tuvf], |
|---|
| 152 | ny[tuvf], firstz[tw], lastz[tw], nz[tw]). |
|---|
| 153 | - points that cannot be computed (domain bondaries, coastline) are set to NaN |
|---|
| 154 | - the common variable jpt is used to differ xyz (jpt=1) and xyt (jpt=1) cases. |
|---|
| 155 | |
|---|
| 156 | |
|---|
| 157 | <h3>Other attributes</h3> |
|---|
| 158 | |
|---|
| 159 | |
|---|
| 160 | <h4>Uses routines</h4> |
|---|
| 161 | cm_4cal, cm_4data, cm_4mmesh |
|---|
| 162 | |
|---|
| 163 | |
|---|
| 164 | |
|---|
| 165 | |
|---|
| 166 | |
|---|
| 167 | <font size="-3"><p> </p></font> |
|---|
| 168 | <hr size="1" color="#CCCCCC"/> |
|---|
| 169 | |
|---|
| 170 | |
|---|
| 171 | |
|---|
| 172 | |
|---|
| 173 | <p><font color="gray" size="-3"> Produced by IDLdoc 2.0 on Wed Sep 13 16:32:08 2006.</font></p> |
|---|
| 174 | |
|---|
| 175 | </body> |
|---|
| 176 | </html> |
|---|
