CLASS = "DASSL"

INCLUDE = "DAE.h"

OPTION
  NAME = "absolute tolerance"
  DOC_ITEM
Absolute tolerance.  May be either vector or scalar.  If a vector, it
must match the dimension of the state vector, and the relative
tolerance must also be a vector of the same length.
  END_DOC_ITEM
  TYPE = "Array<double>"
  SET_ARG_TYPE = "const $TYPE&"
  INIT_BODY
    $OPTVAR.resize (1);
    $OPTVAR(0) = ::sqrt (DBL_EPSILON);
  END_INIT_BODY
  SET_CODE
    void set_$OPT (double val)
      {
        $OPTVAR.resize (1);
        $OPTVAR(0) = (val > 0.0) ? val : ::sqrt (DBL_EPSILON);
        reset = true;
      }

    void set_$OPT (const $TYPE& val)
      { $OPTVAR = val; reset = true; }
  END_SET_CODE
END_OPTION

OPTION
  NAME = "relative tolerance"
  DOC_ITEM
Relative tolerance.  May be either vector or scalar.  If a vector, it
must match the dimension of the state vector, and the absolute
tolerance must also be a vector of the same length.

The local error test applied at each integration step is

@example
  abs (local error in x(i))
       <= rtol(i) * abs (Y(i)) + atol(i)
@end example
  END_DOC_ITEM
  TYPE = "Array<double>"
  SET_ARG_TYPE = "const $TYPE&"
  INIT_BODY
    $OPTVAR.resize (1);
    $OPTVAR(0) = ::sqrt (DBL_EPSILON);
  END_INIT_BODY
  SET_CODE
    void set_$OPT (double val)
      {
        $OPTVAR.resize (1);
        $OPTVAR(0) = (val > 0.0) ? val : ::sqrt (DBL_EPSILON);
        reset = true;
      }

    void set_$OPT (const $TYPE& val)
      { $OPTVAR = val; reset = true; }
  END_SET_CODE
END_OPTION

OPTION
  NAME = "compute consistent initial condition"
  DOC_ITEM
If nonzero, @code{dassl} will attempt to compute a consistent set of intial
conditions.  This is generally not reliable, so it is best to provide
a consistent set and leave this option set to zero.
  END_DOC_ITEM
  TYPE = "octave_idx_type"
  INIT_VALUE = "0"
  SET_EXPR = "val"
END_OPTION

OPTION
  NAME = "enforce nonnegativity constraints"
  DOC_ITEM
If you know that the solutions to your equations will always be
nonnegative, it may help to set this parameter to a nonzero
value.  However, it is probably best to try leaving this option set to
zero first, and only setting it to a nonzero value if that doesn't
work very well.
  END_DOC_ITEM
  TYPE = "octave_idx_type"
  INIT_VALUE = "0"
  SET_EXPR = "val"
END_OPTION

OPTION
  NAME = "initial step size"
  DOC_ITEM
Differential-algebraic problems may occaisionally suffer from severe
scaling difficulties on the first step.  If you know a great deal
about the scaling of your problem, you can help to alleviate this
problem by specifying an initial stepsize.
  END_DOC_ITEM
  TYPE = "double"
  INIT_VALUE = "-1.0"
  SET_EXPR = "(val >= 0.0) ? val : -1.0"
END_OPTION

OPTION
  NAME = "maximum order"
  DOC_ITEM
Restrict the maximum order of the solution method.  This option must
be between 1 and 5, inclusive.
  END_DOC_ITEM
  TYPE = "octave_idx_type"
  INIT_VALUE = "-1"
  SET_EXPR = "val"
END_OPTION

OPTION
  NAME = "maximum step size"
  DOC_ITEM
Setting the maximum stepsize will avoid passing over very large
regions  (default is not specified).
  END_DOC_ITEM
  TYPE = "double"
  INIT_VALUE = "-1.0"
  SET_EXPR = "(val >= 0.0) ? val : -1.0"
END_OPTION

OPTION
  NAME = "step limit"
  DOC_ITEM
Maximum number of integration steps to attempt on a single call to the
underlying Fortran code.
  END_DOC_ITEM
  TYPE = "octave_idx_type"
  INIT_VALUE = "-1"
  SET_EXPR = "(val >= 0) ? val : -1"
END_OPTION