1 | \documentclass[../main/NEMO_manual]{subfiles} |
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2 | |
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3 | \begin{document} |
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4 | % ================================================================ |
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5 | % Appendix D Coding Rules |
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6 | % ================================================================ |
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7 | \chapter{Coding Rules} |
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8 | \label{apdx:D} |
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9 | |
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10 | \minitoc |
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11 | |
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12 | \newpage |
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13 | |
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14 | A "model life" is more than ten years. |
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15 | Its software, composed of a few hundred modules, is used by many people who are scientists or students and |
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16 | do not necessarily know every aspect of computing very well. |
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17 | Moreover, a well thought-out program is easier to read and understand, less difficult to modify, |
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18 | produces fewer bugs and is easier to maintain. |
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19 | Therefore, it is essential that the model development follows some rules: |
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20 | |
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21 | - well planned and designed |
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22 | |
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23 | - well written |
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24 | |
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25 | - well documented (both on- and off-line) |
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26 | |
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27 | - maintainable |
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28 | |
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29 | - easily portable |
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30 | |
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31 | - flexible. |
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32 | |
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33 | To satisfy part of these aims, \NEMO\ is written with a coding standard which is close to the ECMWF rules, |
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34 | named DOCTOR \citep{gibson_trpt86}. |
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35 | These rules present some advantages like: |
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36 | |
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37 | - to provide a well presented program |
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38 | |
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39 | - to use rules for variable names which allow recognition of their type |
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40 | (integer, real, parameter, local or shared variables, etc. ). |
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41 | |
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42 | This facilitates both the understanding and the debugging of an algorithm. |
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43 | |
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44 | % ================================================================ |
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45 | % The program structure |
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46 | % ================================================================ |
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47 | \section{Program structure} |
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48 | \label{sec:D_structure} |
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49 | |
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50 | Each program begins with a set of headline comments containing: |
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51 | |
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52 | - the program title |
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53 | |
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54 | - the purpose of the routine |
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55 | |
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56 | - the method and algorithms used |
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57 | |
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58 | - the detail of input and output interfaces |
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59 | |
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60 | - the external routines and functions used (if they exist) |
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61 | |
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62 | - references (if they exist) |
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63 | |
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64 | - the author name(s), the date of creation and any updates. |
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65 | |
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66 | - Each program is split into several well separated sections and |
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67 | sub-sections with an underlined title and specific labelled statements. |
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68 | |
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69 | - A program has not more than 200 to 300 lines. |
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70 | |
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71 | A template of a module style can be found on the NEMO depository in the following file: |
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72 | NEMO/OPA\_SRC/module\_example. |
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73 | % ================================================================ |
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74 | % Coding conventions |
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75 | % ================================================================ |
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76 | \section{Coding conventions} |
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77 | \label{sec:D_coding} |
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78 | |
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79 | - Use of the universal language \fninety, and try to avoid obsolescent features like statement functions, |
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80 | do not use GO TO and EQUIVALENCE statements. |
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81 | |
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82 | - A continuation line begins with the character {\&} indented by three spaces compared to the previous line, |
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83 | while the previous line ended with the character {\&}. |
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84 | |
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85 | - All the variables must be declared. |
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86 | The code is usually compiled with implicit none. |
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87 | |
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88 | - Never use continuation lines in the declaration of a variable. |
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89 | When searching a variable in the code through a \textit{grep} command, the declaration line will be found. |
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90 | |
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91 | - In the declaration of a PUBLIC variable, the comment part at the end of the line should start with |
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92 | the two characters "\verb?!:?". |
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93 | The following UNIX command, \\ |
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94 | \verb?grep var_name *90 \ grep \!: ? \\ |
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95 | will display the module name and the line where the var\_name declaration is. |
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96 | |
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97 | - Always use a three spaces indentation in DO loop, CASE, or IF-ELSEIF-ELSE-ENDIF statements. |
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98 | |
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99 | - use a space after a comma, except when it appears to separate the indices of an array. |
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100 | |
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101 | - use call to ctl\_stop routine instead of just a STOP. |
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102 | |
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103 | \newpage |
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104 | |
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105 | % ================================================================ |
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106 | % Naming Conventions |
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107 | % ================================================================ |
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108 | \section{Naming conventions} |
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109 | \label{sec:D_naming} |
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110 | |
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111 | The purpose of the naming conventions is to use prefix letters to classify model variables. |
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112 | These conventions allow the variable type to be easily known and rapidly identified. |
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113 | The naming conventions are summarised in the Table below: |
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114 | |
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115 | |
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116 | %--------------------------------------------------TABLE-------------------------------------------------- |
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117 | \begin{table}[htbp] |
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118 | \label{tab:VarName} |
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119 | \begin{center} |
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120 | \begin{tabular}{|p{45pt}|p{35pt}|p{45pt}|p{40pt}|p{40pt}|p{40pt}|p{40pt}|p{40pt}|} |
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121 | \hline |
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122 | Type \par / Status |
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123 | & integer |
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124 | & real |
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125 | & logical |
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126 | & character |
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127 | & structure |
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128 | & double \par precision |
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129 | & complex \\ |
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130 | \hline |
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131 | public \par or \par module variable |
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132 | & \textbf{m n} \par \textit{but not} \par \textbf{nn\_ np\_} |
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133 | & \textbf{a b e f g h o q r} \par \textbf{t} \textit{to} \textbf{x} \par but not \par \textbf{fs rn\_} |
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134 | & \textbf{l} \par \textit{but not} \par \textbf{lp ld} \par \textbf{ ll ln\_} |
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135 | & \textbf{c} \par \textit{but not} \par \textbf{cp cd} \par \textbf{cl cn\_} |
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136 | & \textbf{s} \par \textit{but not} \par \textbf{sd sd} \par \textbf{sl sn\_} |
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137 | & \textbf{d} \par \textit{but not} \par \textbf{dp dd} \par \textbf{dl dn\_} |
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138 | & \textbf{y} \par \textit{but not} \par \textbf{yp yd} \par \textbf{yl yn} \\ |
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139 | \hline |
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140 | dummy \par argument |
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141 | & \textbf{k} \par \textit{but not} \par \textbf{kf} |
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142 | & \textbf{p} \par \textit{but not} \par \textbf{pp pf} |
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143 | & \textbf{ld} |
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144 | & \textbf{cd} |
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145 | & \textbf{sd} |
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146 | & \textbf{dd} |
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147 | & \textbf{yd} \\ |
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148 | \hline |
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149 | local \par variable |
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150 | & \textbf{i} |
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151 | & \textbf{z} |
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152 | & \textbf{ll} |
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153 | & \textbf{cl} |
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154 | & \textbf{sl} |
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155 | & \textbf{dl} |
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156 | & \textbf{yl} \\ |
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157 | \hline |
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158 | loop \par control |
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159 | & \textbf{j} \par \textit{but not} \par \textbf{jp} &&&&&& \\ |
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160 | \hline |
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161 | parameter |
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162 | & \textbf{jp np\_} |
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163 | & \textbf{pp} |
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164 | & \textbf{lp} |
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165 | & \textbf{cp} |
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166 | & \textbf{sp} |
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167 | & \textbf{dp} |
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168 | & \textbf{yp} \\ |
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169 | \hline |
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170 | namelist |
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171 | & \textbf{nn\_} |
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172 | & \textbf{rn\_} |
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173 | & \textbf{ln\_} |
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174 | & \textbf{cn\_} |
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175 | & \textbf{sn\_} |
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176 | & \textbf{dn\_} |
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177 | & \textbf{yn\_} |
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178 | \\ |
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179 | \hline |
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180 | CPP \par macro |
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181 | & \textbf{kf} |
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182 | & \textbf{fs} \par &&&&& \\ |
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183 | \hline |
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184 | \end{tabular} |
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185 | \label{tab:tab1} |
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186 | \end{center} |
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187 | \end{table} |
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188 | %-------------------------------------------------------------------------------------------------------------- |
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189 | |
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190 | N.B. Parameter here, in not only parameter in the \fortran acceptation, |
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191 | it is also used for code variables that are read in namelist and should never been modified during a simulation. |
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192 | It is the case, for example, for the size of a domain (jpi,jpj,jpk). |
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193 | |
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194 | \newpage |
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195 | |
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196 | % ================================================================ |
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197 | % The program structure |
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198 | % ================================================================ |
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199 | %\section{Program structure} |
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200 | %\label{sec:Apdx_D_structure} |
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201 | |
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202 | %To be done.... |
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203 | \biblio |
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204 | |
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205 | \pindex |
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206 | |
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207 | \end{document} |
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