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| 57 | <td><a href="../../../Interpolation//spl_keep_mean.pro" title="Source code of a file">Source</a></td> |
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| 74 | <a href="spl_incr.html"><<prev file</a> | <a href="square2quadrilateral.html">next file >></a> <a href="spl_keep_mean.html" target="_TOP">view single page</a> | <a href="./../index.html" target="_TOP">view frames</a> summary: fields | routine details: <a href="#routine_details">routine</a> |
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| 81 | <h1 class="directory"><a href="directory-overview.html">Interpolation/</a></h1> |
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| 82 | <h2 class="pro_file">spl_keep_mean.pro</h2> |
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| 86 | </dl> |
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| 88 | |
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| 89 | <div id="file_comments"> |
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| 90 | Given the arrays X and Y, which tabulate a function (with the X[i] |
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| 91 | AND Y[i] in ascending order), and given an input value X2, the |
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| 92 | <a href="..//Interpolation/spl_incr.html">spl_incr</a> function returns an interpolated value for the given values |
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| 93 | of X2. The interpolation method is based on cubic spline, corrected |
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| 94 | in a way that integral of the interpolated values is the same as the |
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| 95 | integral of the input values. (-> for example to build daily data |
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| 96 | from monthly mean and keep the monthly mean of the computed daily |
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| 97 | data equal to the original values) |
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| 98 | </div> |
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| 99 | |
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| 100 | |
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| 101 | |
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| 102 | |
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| 103 | |
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| 105 | |
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| 106 | |
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| 107 | |
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| 108 | <div id="routine_details"> |
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| 109 | |
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| 110 | |
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| 111 | <div class="routine_details" id="_spl_keep_mean"> |
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| 112 | |
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| 113 | <h2><a class="top" href="#container">top</a>spl_keep_mean </h2> |
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| 114 | |
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| 115 | <p class="header"> |
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| 116 | <span class="result">result = </span>spl_keep_mean(<span class="result"><a href="#_spl_keep_mean_param_x">x</a>, <a href="#_spl_keep_mean_param_yin">yin</a>, <a href="#_spl_keep_mean_param_x2">x2</a></span>, <a href="#_spl_keep_mean_keyword_YP0">YP0</a>=<span class="result">YP0</span>, <a href="#_spl_keep_mean_keyword_YPN_1">YPN_1</a>=<span class="result">YPN_1</span>, <a href="#_spl_keep_mean_keyword_GE0">GE0</a>=<span class="result">GE0</span>)</p> |
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| 117 | |
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| 118 | <div class="comments"> |
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| 119 | </div> |
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| 120 | |
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| 121 | <h3>Return value</h3><div class="preformat"> |
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| 122 | y2: the mean value between two consecutive values of x2. This |
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| 123 | array has one element less than y2. y2 has double precision. |
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| 124 | </div> |
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| 125 | |
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| 126 | |
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| 127 | <h3>Parameters</h3> |
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| 128 | |
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| 129 | |
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| 130 | <h4 id="_spl_keep_mean_param_x">x |
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| 131 | <span class="attr">in</span> |
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| 132 | |
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| 133 | |
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| 134 | <span class="attr">required</span> |
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| 135 | |
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| 136 | |
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| 137 | |
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| 138 | |
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| 139 | </h4> |
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| 140 | |
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| 141 | <div class="comments"> |
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| 142 | An n-elements (at least 2) input vector that specifies the tabulate points in |
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| 143 | a strict ascending order. |
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| 144 | </div> |
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| 145 | |
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| 146 | <h4 id="_spl_keep_mean_param_yin">yin |
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| 147 | <span class="attr">in</span> |
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| 148 | |
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| 149 | |
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| 150 | <span class="attr">required</span> |
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| 151 | |
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| 152 | <span class="attr">type:</span> <span class="value">array</span> |
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| 153 | |
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| 154 | |
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| 155 | </h4> |
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| 156 | |
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| 157 | <div class="comments"> |
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| 158 | an array with one element less than x. y[i] represents the |
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| 159 | mean value between x[i] and x[i+1]. if /GE0 is activated, y must |
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| 160 | have positive values. |
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| 161 | </div> |
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| 162 | |
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| 163 | <h4 id="_spl_keep_mean_param_x2">x2 |
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| 164 | <span class="attr">in</span> |
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| 165 | |
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| 166 | |
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| 167 | <span class="attr">required</span> |
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| 168 | |
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| 169 | |
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| 170 | |
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| 171 | |
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| 172 | </h4> |
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| 173 | |
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| 174 | <div class="comments"> |
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| 175 | The input values for which the interpolated values are desired. |
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| 176 | Its values must be strictly monotonically increasing. |
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| 177 | </div> |
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| 178 | |
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| 179 | |
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| 180 | |
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| 181 | |
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| 182 | |
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| 183 | |
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| 184 | <h3>Keywords</h3> |
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| 185 | |
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| 186 | <h4 id="_spl_keep_mean_keyword_YP0">YP0 |
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| 187 | |
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| 188 | |
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| 189 | |
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| 190 | |
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| 191 | |
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| 192 | |
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| 193 | |
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| 194 | |
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| 195 | </h4> |
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| 196 | |
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| 197 | <div class="comments"> |
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| 198 | The first derivative of the interpolating function at the |
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| 199 | point X0. If YP0 is omitted, the second derivative at the |
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| 200 | boundary is set to zero, resulting in a "natural spline." |
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| 201 | </div> |
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| 202 | |
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| 203 | <h4 id="_spl_keep_mean_keyword_YPN_1">YPN_1 |
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| 204 | |
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| 205 | |
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| 206 | |
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| 208 | |
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| 209 | |
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| 210 | |
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| 211 | |
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| 212 | </h4> |
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| 213 | |
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| 214 | <div class="comments"> |
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| 215 | The first derivative of the interpolating function at the |
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| 216 | point Xn-1. If YPN_1 is omitted, the second derivative at the |
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| 217 | boundary is set to zero, resulting in a "natural spline." |
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| 218 | </div> |
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| 219 | |
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| 220 | <h4 id="_spl_keep_mean_keyword_GE0">GE0 |
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| 221 | |
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| 222 | |
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| 223 | |
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| 224 | |
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| 225 | |
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| 226 | |
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| 227 | |
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| 228 | |
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| 229 | </h4> |
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| 230 | |
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| 231 | <div class="comments"> |
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| 232 | to force that y2 is always GE than 0. In that case, y must also be GE than 0. |
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| 233 | </div> |
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| 234 | |
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| 235 | |
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| 236 | |
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| 237 | <h3>Examples</h3><div class="preformat"> |
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| 238 | |
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| 239 | 12 monthly values of precipitations into daily values: |
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| 240 | |
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| 241 | IDL> yr1 = 1990 |
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| 242 | IDL> yr2 = 1992 |
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| 243 | IDL> nyr = yr2-yr1+1 |
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| 244 | IDL> n1 = 12*nyr+1 |
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| 245 | IDL> x = julday(1+findgen(n1), replicate(1, n1) $ |
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| 246 | IDL> , replicate(yr1, n1), fltarr(n1)) |
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| 247 | IDL> n2 = 365*nyr + total(leapyr(yr1+indgen(nyr))) + 1 |
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| 248 | IDL> x2 = julday(replicate(1, n2), 1+findgen(n2) $ |
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| 249 | IDL> , replicate(yr1, n2), fltarr(n2)) |
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| 250 | IDL> y = abs(randomn(0, n1-1)) |
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| 251 | IDL> y2 = spl_keep_mean(x, y, x2, /ge0) |
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| 252 | |
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| 253 | IDL> print, min(x, max = ma), ma |
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| 254 | IDL> print, min(x2, max = ma), ma |
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| 255 | IDL> print, vairdate([min(x, max = ma), ma]) |
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| 256 | IDL> print, total(y*(x[1:n1-1]-x[0:n1-2])) |
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| 257 | IDL> print, total(y2*(x2[1:n2-1]-x2[0:n2-2])) |
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| 258 | </div> |
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| 259 | <h3>Version history</h3> |
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| 260 | |
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| 261 | <h4>Version</h4><div class="preformat"> |
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| 262 | $Id: spl_keep_mean.pro 372 2008-08-08 12:31:53Z pinsard $ |
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| 263 | </div> |
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| 264 | <h4>History</h4><div class="preformat"> |
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| 265 | Sebastien Masson (smasson@lodyc.jussieu.fr): May 2005 |
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| 266 | </div> |
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| 267 | |
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| 268 | |
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| 269 | <h3>Known issues</h3> |
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| 270 | |
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| 271 | |
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| 272 | |
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| 273 | <h4>Restrictions</h4><div class="preformat"> |
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| 274 | It might be possible that y2 has very small negative values |
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| 275 | (amplitude smaller than 1.e-6)... |
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| 276 | </div> |
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| 277 | |
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| 278 | |
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| 281 | |
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| 282 | |
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| 283 | |
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| 284 | |
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| 285 | |
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| 286 | <h3>Statistics</h3> |
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| 287 | <table class="statistics"> |
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| 288 | <tr><td>McCabe cyclic</td><td> 8</td></tr> |
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| 289 | <tr><td>McCabe essential</td><td> 1</td></tr> |
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| 290 | <tr><td>McCabe modular design</td><td> 1</td></tr> |
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| 291 | </table> |
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| 292 | |
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| 293 | |
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| 294 | </div> |
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| 295 | |
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| 296 | </div> |
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| 297 | |
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| 298 | |
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| 299 | |
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| 300 | <div id="tagline">Produced by IDLdoc 2.0.</div> |
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