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# Parameter Management

int GRBgetdblparam(GRBenv *env, const char *paramname, double *valueP)

  Retrieve the value of a double-valued parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to query the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while retrieving the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being queried.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - valueP – The location in which the current value of the requested parameter should be placed.

  Example:

        double cutoff;
        error = GRBgetdblparam(GRBgetenv(model), "Cutoff", &cutoff);

int GRBgetintparam(GRBenv *env, const char *paramname, int *valueP)

  Retrieve the value of an integer-valued parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to query the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while retrieving the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being queried.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - valueP – The location in which the current value of the requested parameter should be placed.

  Example:

        int limit;
        error = GRBgetintparam(GRBgetenv(model), "SolutionLimit", &limit);

int GRBgetstrparam(GRBenv *env, const char *paramname, char *value)

  Retrieve the value of a string-valued parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to query the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while retrieving the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being queried.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - value – The location in which the current value of the requested parameter should be placed.

  Example:

        char logfilename[GRB_MAX_STRLEN];
        error = GRBgetstrparam(GRBgetenv(model), "LogFile", logfilename);

int GRBsetdblparam(GRBenv *env, const char *paramname, double newvalue)

  Modify the value of a double-valued parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to change the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while modifying the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being modified.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - newvalue – The desired new value of the parameter.

  Example:

        error = GRBsetdblparam(GRBgetenv(model), "Cutoff", 100.0);

int GRBsetintparam(GRBenv *env, const char *paramname, int newvalue)

  Modify the value of an integer-valued parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to change the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while modifying the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being modified.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - newvalue – The desired new value of the parameter.

  Example:

        error = GRBsetintparam(GRBgetenv(model), "SolutionLimit", 5);

int GRBsetstrparam(GRBenv *env, const char *paramname, const char *newvalue)

  Modify the value of a string-valued parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to change the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while modifying the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being modified.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - newvalue – The desired new value of the parameter.

  Example:

        error = GRBsetstrparam(GRBgetenv(model), "LogFile", "/tmp/new.log");

int GRBsetparam(GRBenv *env, const char *paramname, const char *newvalue)

  Modify the value of a parameter.

  Note that a model gets its own copy of the environment when it is created. Changes to the original environment have no effect on the copy, and vice versa. Use `GRBgetenv` to retrieve the environment associated with a model if you would like to change the parameter value for that model.

  Return value:

    A non-zero return value indicates that a problem occurred while modifying the parameter. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter value is being modified.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - newvalue – The desired new value of the parameter.

  Example:

        error = GRBsetparam(GRBgetenv(model), "Cutoff", "100.0");

int GRBgetdblparaminfo(GRBenv *env, const char *paramname, double *valueP, double *minP, double *maxP, double *defaultP)

  Retrieve information about a double-valued parameter. Specifically, retrieve the current value of the parameter, the minimum and maximum allowed values, and the default value.

  Return value:

    A non-zero return value indicates that a problem occurred while retrieving parameter information. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter information is being queried.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - valueP – (optional) The location in which the current value of the specified parameter should be placed.

    - minP – (optional) The location in which the minimum allowed value of the specified parameter should be placed.

    - maxP – (optional) The location in which the maximum allowed value of the specified parameter should be placed.

    - defaultP – (optional) The location in which the default value of the specified parameter should be placed.

  Example:

        error = GRBgetdblparaminfo(GRBgetenv(model), "MIPGap", &currentGap,
                                   &minAllowedGap, NULL, &defaultGap);

int GRBgetintparaminfo(GRBenv *env, const char *paramname, int *valueP, int *minP, int *maxP, int *defaultP)

  Retrieve information about an int-valued parameter. Specifically, retrieve the current value of the parameter, the minimum and maximum allowed values, and the default value.

  Return value:

    A non-zero return value indicates that a problem occurred while retrieving parameter information. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter information is being queried.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - valueP – (optional) The location in which the current value of the specified parameter should be placed.

    - minP – (optional) The location in which the minimum allowed value of the specified parameter should be placed.

    - maxP – (optional) The location in which the maximum allowed value of the specified parameter should be placed.

    - defaultP – (optional) The location in which the default value of the specified parameter should be placed.

  Example:

        error = GRBgetintparaminfo(GRBgetenv(model), "SolutionLimit", &current,
                                   &minAllowedLimit, NULL, &defaultLimit);

int GRBgetstrparaminfo(GRBenv *env, const char *paramname, char *value, char *defaultP)

  Retrieve information about a string-valued parameter. Specifically, retrieve the current and default values of the parameter.

  Return value:

    A non-zero return value indicates that a problem occurred while retrieving parameter information. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter information is being queried.

    - paramname – The name of the parameter. Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

    - value – (optional) The location in which the current value of the specified parameter should be placed.

    - defaultP – (optional) The location in which the default value of the specified parameter should be placed.

  Example:

        char defaultval[GRB_MAX_STRLEN];
        char currentval[GRB_MAX_STRLEN];
        error = GRBgetstrparaminfo(GRBgetenv(model), "LogFile", currentval,
                                   defaultval);

int GRBreadparams(GRBenv *env, const char *filename)

  Import a set of parameter modifications from a file.

  Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

  Return value:

    A non-zero return value indicates that a problem occurred while reading the parameter file. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment into which the parameter changes should be imported.

    - filename – The path to the file to be read. The suffix on a parameter file should be `.prm`, optionally followed by `.zip`, `.gz`, `.bz2`, `.7z` or `.xz`.

  Example:

        error = GRBreadparams(env, "/tmp/model.prm.bz2");

int GRBresetparams(GRBenv *env)

  Reset the values of all parameters to their default values.

  Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

  Return value:

    A non-zero return value indicates that a problem occurred while resetting parameters. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment for which the parameters should be reset to their default value.

  Example:

        error = GRBresetparams(env);

int GRBwriteparams(GRBenv *env, const char *filename)

  Write the set of changed parameter values to a file.

  Please consult the parameter section for a complete list of Gurobi parameters, including descriptions of their purposes and their minimum, maximum, and default values.

  Return value:

    A non-zero return value indicates that a problem occurred while writing the parameter file. Refer to the Error Codes table for a list of possible return values. Details on the error can be obtained by calling `GRBgeterrormsg`.

  Arguments:

    - env – The environment whose parameter changes are being written.

    - filename – The path to the file to be written. The suffix on a parameter file should be `.prm`, optionally followed by `.zip`, `.gz`, `.bz2`, `.7z` or `.xz`.

  Example:

        error = GRBwriteparams(env, "/tmp/model.prm");

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