1 | #include "Python.h" |
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2 | #include "Numeric/arrayobject.h" |
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3 | #include "math.h" |
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4 | #include <stdio.h> |
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5 | const double pi = 3.14159265358979; |
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6 | |
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7 | double max(double a, double b) { |
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8 | double z; |
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9 | z=(a>b)?a:b; |
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10 | return z;} |
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11 | |
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12 | double min(double a, double b) { |
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13 | double z; |
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14 | z=(a<b)?a:b; |
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15 | return z;} |
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16 | |
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17 | |
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18 | //Innermost flux function (using w=z+h) |
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19 | int _flux_function(double *q_left, double *q_right, |
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20 | double z_left, double z_right, |
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21 | double normals, double g, double epsilon, |
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22 | double *edgeflux, double *max_speed) { |
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23 | |
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24 | int i; |
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25 | double ql[2], qr[2], flux_left[2], flux_right[2]; |
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26 | double z, w_left, h_left, uh_left, soundspeed_left, u_left; |
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27 | double w_right, h_right, uh_right, soundspeed_right, u_right; |
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28 | double s_max, s_min, denom; |
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29 | |
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30 | |
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31 | ql[0] = q_left[0]; |
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32 | ql[1] = q_left[1]; |
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33 | ql[1] = ql[1]*normals; |
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34 | |
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35 | qr[0] = q_right[0]; |
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36 | qr[1] = q_right[1]; |
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37 | qr[1] = qr[1]*normals; |
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38 | |
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39 | z = (z_left+z_right)/2.0; |
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40 | |
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41 | w_left = ql[0]; |
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42 | h_left = w_left-z; |
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43 | uh_left = ql[1]; |
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44 | |
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45 | |
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46 | |
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47 | // Compute speeds in x-direction |
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48 | w_left = ql[0]; |
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49 | h_left = w_left-z; |
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50 | uh_left = ql[1]; |
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51 | if (h_left < epsilon) { |
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52 | u_left = 0.0; h_left = 0.0; |
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53 | } |
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54 | else { |
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55 | u_left = uh_left/h_left; |
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56 | } |
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57 | |
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58 | w_right = qr[0]; |
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59 | h_right = w_right-z; |
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60 | uh_right = qr[1]; |
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61 | if (h_right < epsilon) { |
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62 | u_right = 0.0; h_right = 0.0; |
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63 | } |
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64 | else { |
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65 | u_right = uh_right/h_right; |
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66 | } |
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67 | |
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68 | soundspeed_left = sqrt(g*h_left); |
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69 | soundspeed_right = sqrt(g*h_right); |
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70 | |
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71 | s_max = max(u_left+soundspeed_left, u_right+soundspeed_right); |
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72 | if (s_max < 0.0) s_max = 0.0; |
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73 | |
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74 | s_min = min(u_left-soundspeed_left, u_right-soundspeed_right); |
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75 | if (s_min > 0.0) s_min = 0.0; |
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76 | |
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77 | |
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78 | // Flux formulas |
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79 | flux_left[0] = u_left*h_left; |
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80 | flux_left[1] = u_left*uh_left + 0.5*g*h_left*h_left; |
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81 | |
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82 | flux_right[0] = u_right*h_right; |
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83 | flux_right[1] = u_right*uh_right + 0.5*g*h_right*h_right; |
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84 | |
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85 | // Flux computation |
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86 | denom = s_max-s_min; |
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87 | if (denom < epsilon) { |
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88 | for (i=0; i<2; i++) edgeflux[i] = 0.0; |
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89 | *max_speed = 0.0; |
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90 | } else { |
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91 | edgeflux[0] = s_max*flux_left[0] - s_min*flux_right[0]; |
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92 | edgeflux[0] += s_max*s_min*(qr[0]-ql[0]); |
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93 | edgeflux[0] /= denom; |
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94 | edgeflux[1] = s_max*flux_left[1] - s_min*flux_right[1]; |
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95 | edgeflux[1] += s_max*s_min*(qr[1]-ql[1]); |
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96 | edgeflux[1] /= denom; |
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97 | edgeflux[1] *= normals; |
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98 | |
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99 | // Maximal wavespeed |
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100 | *max_speed = max(fabs(s_max), fabs(s_min)); |
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101 | } |
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102 | return 0; |
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103 | } |
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104 | |
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105 | |
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106 | |
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107 | |
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108 | // Computational function for flux computation |
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109 | double _compute_fluxes_ext(double timestep, |
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110 | double epsilon, |
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111 | double g, |
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112 | long* neighbours, |
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113 | long* neighbour_vertices, |
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114 | double* normals, |
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115 | double* areas, |
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116 | double* stage_edge_values, |
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117 | double* xmom_edge_values, |
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118 | double* bed_edge_values, |
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119 | double* stage_boundary_values, |
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120 | double* xmom_boundary_values, |
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121 | double* stage_explicit_update, |
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122 | double* xmom_explicit_update, |
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123 | int number_of_elements, |
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124 | double* max_speed_array) { |
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125 | |
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126 | double flux[2], ql[2], qr[2], edgeflux[2]; |
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127 | double zl, zr, max_speed, normal; |
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128 | int k, i, ki, n, m, nm=0; |
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129 | |
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130 | for (k=0; k<number_of_elements; k++) { |
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131 | flux[0] = 0.0; |
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132 | flux[1] = 0.0; |
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133 | |
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134 | for (i=0; i<2; i++) { |
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135 | ki = k*2+i; |
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136 | |
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137 | ql[0] = stage_edge_values[ki]; |
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138 | ql[1] = xmom_edge_values[ki]; |
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139 | zl = bed_edge_values[ki]; |
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140 | |
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141 | n = neighbours[ki]; |
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142 | if (n<0) { |
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143 | m = -n-1; |
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144 | qr[0] = stage_boundary_values[m]; |
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145 | qr[1] = xmom_boundary_values[m]; |
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146 | zr = zl; |
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147 | } else { |
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148 | m = neighbour_vertices[ki]; |
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149 | nm = n*2+m; |
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150 | qr[0] = stage_edge_values[nm]; |
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151 | qr[1] = xmom_edge_values[nm]; |
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152 | zr = bed_edge_values[nm]; |
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153 | } |
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154 | |
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155 | normal = normals[ki]; |
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156 | _flux_function(ql, qr, zl, zr, normal, g, epsilon, flux, &max_speed); |
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157 | flux[0] -= edgeflux[0]; |
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158 | flux[1] -= edgeflux[1]; |
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159 | |
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160 | // Update timestep based on edge i and possibly neighbour n |
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161 | if (max_speed > epsilon) { |
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162 | // Original CFL calculation |
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163 | |
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164 | timestep = min(timestep, 0.5*areas[k]/max_speed); //Here, CFL=1.0 is assumed. ????????????????????????????????????????????? |
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165 | if (n>=0) { |
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166 | timestep = min(timestep, 0.5*areas[n]/max_speed); //Here, CFL=1.0 is assumed. ????????????????????????????????????????????? |
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167 | } |
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168 | } |
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169 | } // End edge i (and neighbour n) |
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170 | flux[0] /= areas[k]; |
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171 | stage_explicit_update[k] = flux[0]; |
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172 | flux[1] /= areas[k]; |
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173 | xmom_explicit_update[k] = flux[1]; |
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174 | |
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175 | //Keep track of maximal speeds |
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176 | max_speed_array[k]=max_speed; |
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177 | } |
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178 | return timestep; } |
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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 | |
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185 | |
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186 | |
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187 | //========================================================================= |
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188 | // Python Glue |
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189 | //========================================================================= |
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190 | PyObject *compute_fluxes_ext(PyObject *self, PyObject *args) { |
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191 | PyArrayObject *neighbours, |
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192 | *neighbour_vertices, |
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193 | *normals, |
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194 | *areas, |
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195 | *stage_edge_values, |
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196 | *xmom_edge_values, |
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197 | *bed_edge_values, |
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198 | *stage_boundary_values, |
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199 | *xmom_boundary_values, |
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200 | *stage_explicit_update, |
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201 | *xmom_explicit_update, |
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202 | *max_speed_array; |
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203 | |
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204 | double timestep, epsilon, g; |
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205 | int number_of_elements; |
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206 | |
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207 | // Convert Python arguments to C |
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208 | if (!PyArg_ParseTuple(args, "dddOOOOOOOOOOOiO", |
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209 | ×tep, |
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210 | &epsilon, |
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211 | &g, |
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212 | &neighbours, |
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213 | &neighbour_vertices, |
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214 | &normals, |
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215 | &areas, |
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216 | &stage_edge_values, |
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217 | &xmom_edge_values, |
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218 | &bed_edge_values, |
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219 | &stage_boundary_values, |
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220 | &xmom_boundary_values, |
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221 | &stage_explicit_update, |
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222 | &xmom_explicit_update, |
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223 | &number_of_elements, |
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224 | &max_speed_array)) { |
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225 | PyErr_SetString(PyExc_RuntimeError, "comp_flux_ext.c: compute_fluxes_ext could not parse input"); |
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226 | return NULL; |
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227 | } |
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228 | |
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229 | |
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230 | // Call underlying flux computation routine and update |
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231 | // the explicit update arrays |
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232 | timestep = _compute_fluxes_ext(timestep, |
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233 | epsilon, |
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234 | g, |
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235 | (long*) neighbours -> data, |
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236 | (long*) neighbour_vertices -> data, |
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237 | (double*) normals -> data, |
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238 | (double*) areas -> data, |
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239 | (double*) stage_edge_values -> data, |
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240 | (double*) xmom_edge_values -> data, |
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241 | (double*) bed_edge_values -> data, |
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242 | (double*) stage_boundary_values -> data, |
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243 | (double*) xmom_boundary_values -> data, |
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244 | (double*) stage_explicit_update -> data, |
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245 | (double*) xmom_explicit_update -> data, |
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246 | number_of_elements, |
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247 | (double*) max_speed_array -> data); |
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248 | // Return updated flux timestep |
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249 | return Py_BuildValue("d", timestep); |
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250 | } |
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251 | |
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252 | |
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253 | |
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254 | |
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255 | //------------------------------- |
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256 | // Method table for python module |
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257 | //------------------------------- |
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258 | |
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259 | static struct PyMethodDef MethodTable[] = { |
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260 | {"compute_fluxes_ext", compute_fluxes_ext, METH_VARARGS, "Print out"}, |
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261 | {NULL, NULL} |
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262 | }; |
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263 | |
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264 | // Module initialisation |
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265 | void initcomp_flux_ext(void){ |
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266 | Py_InitModule("comp_flux_ext", MethodTable); |
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267 | import_array(); |
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268 | } |
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