Changes between Version 9 and Version 10 of AthenaDocsUGUserExpress


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Timestamp:
06/08/10 16:50:44 (4 years ago)
Author:
jmstone
Comment:

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  • AthenaDocsUGUserExpress

    v9 v10  
    22 
    33'''[wiki:AthenaDocs Documentation]/[wiki:AthenaDocsUG UserGuide]/User Variables''' 
     4 
     5== New Variables added to .tab, .bin, .vtk, or image (.ppm or .pgm) outputs == 
    46 
    57Often it is useful to output a variable other than the pre-defined values accessed by the 
     
    1012following steps are required. 
    1113 
    12 First, write a function that computes the desired variable, and add it to the file that contains the  
     141. Write a function that computes the desired variable, and add it to the file that contains the  
    1315problem generator.  The function must be of 
    1416type {{{Real}}}, and the argument list must contain the {{{GridS}}} 
     
    2527}}} 
    2628 
    27 Next, use the function {{{get_usr_expr()}}} in the 
     292. Use the function {{{get_usr_expr()}}} in the 
    2830problem generator file to set a pointer to this new function if the 
    2931string in {{{<output>/out}}} has the appropriate value.  As an example, the following code sets the output variable to be 
     
    3840}}} 
    3941 
    40 Finally, to create a movie of the current density, use an output block in the input 
     423. To create a movie of the current density, use an output block in the input 
    4143file in which {{{<output>/out=J3}}}, and {{{<output>/usr_expr_flag=1}}}, 
    4244with the other valid parameters set as appropriate (to control, for 
     
    5557Alternatively, one could output the current density as floating-point numbers in vtk format using {{{out_fmt=vtk}}}, or as a formatted table using 
    5658{{{out_fmt=tab}}}. 
     59 
     60== New Variables added to .hst dumps == 
     61 
     62It is also possible to add new volume-averaged quantities that are output as additional columns in history (.hst) dumps. 
     63To add a new, user-defined history variable, use the following steps. 
     64 
     651. Write a function that computes the desired variable, and add it to the file that contains the  
     66problem generator, identical to step 1 above for all other output types. 
     67 
     682. Enroll this new function by adding a call to {{{dump_history_enroll()}}} anywhere in the problem generator.  This function has two arguments, 
     69the first is the name of the function created in step 1, the second is a string used as a header for the new column in the history file.  For example, 
     70the following four lines of code in the problem generator enroll four new history variables. 
     71{{{ 
     72  dump_history_enroll(hst_Bx, "<Bx>"); 
     73  dump_history_enroll(hst_By, "<By>"); 
     74  dump_history_enroll(hst_Bz, "<Bz>"); 
     75  dump_history_enroll(hst_BxBy, "<-Bx By>"); 
     76}}} 
     77These variables are computed by the user-defined functions {{{hst_Bx()}}}, {{{hst_By()}}}, {{{hst_Bz()}}}, and {{{hst_BxBy()}}} respectively, 
     78and create new columns with headers {{{<Bx>}}}, {{{<By>}}}, {{{<Bz>}}}, and {{{<-Bx By>}}} respectively.