{"id":607,"date":"2022-04-05T14:47:54","date_gmt":"2022-04-05T13:47:54","guid":{"rendered":"http:\/\/perf.unime.it\/magnet\/?page_id=607"},"modified":"2022-04-20T07:44:24","modified_gmt":"2022-04-20T06:44:24","slug":"model-analysis","status":"publish","type":"page","link":"http:\/\/perf.unime.it\/magnet\/?page_id=607","title":{"rendered":"Model analysis"},"content":{"rendered":"\n

Current version of MagNet implements transient analysis of Markovian agent based models. The analysis is arranged throughout some parameters to set before the starting of the analysis. Parameter names, C type to use for their definition, their semantics, and their default values are summarized in the following table:<\/p>\n\n\n\n

Parameter name<\/th>C type<\/th>Default value<\/th>Semantics<\/th><\/tr><\/thead>
SOLUTION_START_TIME<\/td>Time<\/td>0.0<\/td>starting time point value in transient analysis evaluation<\/td><\/tr>
SOLUTION_END_TIME<\/td>Time<\/td>0.0<\/td>final time point value in transient analysis evaluation<\/td><\/tr>
SOLUTION_STEP<\/td>Step<\/td>0.0<\/td>advancement step used in transient analysis evaluation<\/td><\/tr>
SOLUTION_TOL<\/td>Tolerance<\/td>10\n -6<\/sup>\n <\/td>tolerance level used to compare values used in numerical algorithms <\/td><\/tr>
SOLUTION_MAX_ITERATIONS<\/td>unsigned int<\/td>20<\/td>maximum number of possible iterations; the iteration is stopped when this value is reached\n
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used with Euler methods only<\/strong>, ignored if othe methods are selected\n
\n <\/td><\/tr>
SOLUTION_THREADS<\/td>unsigned int<\/td>1<\/td>number of threads to generate if the implementation of the selected method supports multi-threading<\/td><\/tr>
SOLUTION_ALG<\/td>SolveType<\/td>OLE_2_RKF45<\/td>type of solution method to use in the transient ananlysis<\/td><\/tr>
OUTPUT<\/td>OUT_Mode<\/td>NO_MODE<\/td>how the results are shown<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Where the multi-threading is supported, the number of thread MagNet uses is computed at runtime. In the current version, multi-threading is implemented in the Forward Euler (explicit) method and backward Euler (implicit) method.
The values different parameters can have are as in the following table<\/a>; when a value is not set the default value written above<\/a> are assumed.<\/p>\n\n\n\n

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Parameter name<\/th>Range<\/th>Note<\/th><\/tr><\/thead>
SOLUTION_START_TIME<\/td>>=0.0 <\/td><\/td><\/tr>
SOLUTION_END_TIME<\/td>>=0.0 <\/td>it is user responsibility to verify that SOLUTION_END_TIME is greater than SOLUTION_START_TIME<\/td><\/tr>
SOLUTION_STEP<\/td>>=0.0 <\/td><\/td><\/tr>
SOLUTION_TOL<\/td>>=0.0 <\/td><\/td><\/tr>
SOLUTION_MAX_ITERATIONS<\/td>> 0<\/td><\/td><\/tr>
SOLUTION_THREADS<\/td>>=0<\/td><\/td><\/tr>
SOLUTION_ALG<\/td>EEULER<\/td>Forward Euler (explicit) method <\/td><\/tr>
<\/td>IEULER<\/td>Backward Euler (implicit) method<\/td><\/tr>
<\/td>OLE2_RK2<\/td>The GSL explicit embedded Runge-Kutta (2, 3) method<\/td><\/tr>
<\/td>OLE2_RK4<\/td>The GSL explicit 4th order Runge-Kutta<\/td><\/tr>
<\/td>OLE2_RKF45<\/td>The GSL explicit embedded Runge-Kutta-Fehlberg (4, 5) method<\/td><\/tr>
<\/td>OLE2_RKCK<\/td>The GSL explicit embedded Runge-Kutta Cash-Karp (4, 5) method<\/td><\/tr>
<\/td>OLE2_RK8PD<\/td>The GSL explicit embedded Runge-Kutta Prince-Dormand (8, 9)<\/td><\/tr>
OUTPUT<\/td>W_MODE<\/td>Density vectors are written in a set of files, one per deployed agent<\/td><\/tr>
<\/td>NO_MODE<\/td>No file is produced<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

When W_MODE is used as OUTPUT, MagNET generate one file per agent whose names are agent_name.csv<\/code>, where agent_name<\/code> is the same string used as name when the Markovian agent is created with m3am_NewAgent<\/code>.<\/p>\n\n\n\n


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Error m3am_SetParams(M3AM *m, ParType Pt, void *val);<\/strong><\/code><\/pre>\n\n\n\n
m3am_SetParams<\/code> sets the parameter Pt<\/code> of the model m<\/code> to the value val<\/code>. Pt<\/code> is one of the values in column Name<\/strong> of the table<\/a>. The value of a model parameter is passed by reference by using a generic pointer to void, thus the most appropriate way is to use a variable defined as appropriate type according to the model parameter the user want to set and then pass its reference as second parameter of m3am_SetParams<\/code>. Here is an example where 10.0 and forward Euler method are set as final time point and solution method respectively when “My_Markovian_Agent_model” is solved<\/p>\n\n\n\n
\nmyModel=m3am_NewModel(\"My_Markovian_Agent_model\", 2);\n  .\n  .\n  .\ndouble p=5.0;\nm3am_SetParams(VoIP, SOLUTION_END_TIME, &p);\nSolveType p3=IEULER;\nm3am_SetParams(VoIP, SOLUTION_ALG, &p3);\n  .\n  .\n<\/code><\/pre>\n\n\n\n
   
                     <\/p>\n\n\n\n
Error m3am_Solve(M3AM *m);<\/strong><\/code><\/pre>\n\n\n\n
m3am_Solve<\/code> performs the transient analysis of the model referenced by m<\/code> from SOLUTION_START_TIME to SOLUTION_END_TIME using the parameter values previously set. The vectors defined with m3am_AddInitProb<\/code> together with the density value used in m3am_NewAgent<\/code> contribute to create the initial density state used as boundary conditions for the transient analysis. The results can be recovered throughout the set of files generated setting OUTPUT parameter to W_MODE, otherwise the vectors of density values at SOLUTION_END_TIME only can be recovered by using m3amGetAgentDensities<\/a><\/code> function.<\/p>\n\n\n\n
  
                     <\/p>\n\n\n\n
Vector *m3am_GetAgentDensities(M3AM *m, const char *ma_label)<\/strong><\/code><\/code><\/pre>\n\n\n\n
m3am_GetAgentDensities<\/code> gets back a vector storing the densities of an agent, whose name is ma_label<\/code>, in the model referenced by m at last evaluated time point.

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Current version of MagNet implements transient analysis of Markovian agent based models. The analysis is arranged throughout some parameters to set before […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-607","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=\/wp\/v2\/pages\/607","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=607"}],"version-history":[{"count":21,"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=\/wp\/v2\/pages\/607\/revisions"}],"predecessor-version":[{"id":779,"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=\/wp\/v2\/pages\/607\/revisions\/779"}],"wp:attachment":[{"href":"http:\/\/perf.unime.it\/magnet\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=607"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}