Interp

Interp is a feature made specifically for users of the COMSOL API and does not appear in the COMSOL Multiphysics GUI. Interp combines cut points and evaluation features, as well as allowing evaluation of arbitrary datasets. It supports multiple expressions and some additional advanced properties not available when using cut points and EvalPoint features.

result = model.result().numerical(<ftag>).getData() returns the real part of the result, recomputing the feature if necessary. result is a three-dimensional double matrix ordered result[expression][solnum][coordinates].

model.result().numerical(<ftag>).getData(<expressionIndex>) returns the real part of the result for one expression, equivalent to result[expressionIndex].

result = model.result().numerical(<ftag>).getImagData() returns the imaginary part of the result, recomputing the feature if necessary. result is a three-dimensional double matrix ordered result[expression][solnum][coordinates].

model.result().numerical(<ftag>).getImagData(<expressionIndex>) returns the imaginary part of the result for one expression, equivalent to result[expressionIndex].

model.result().numerical(<ftag>).isComplex() returns true if the result is complex. The resulting value is a scalar, which true if any of the expressions in an array is complex-valued.

model.result().numerical(<ftag>).isComplex(<outersolnum>) returns true if the result is complex for the given outer solution. <outersolnum> is applicable only for parametric sweep solutions and is the index of each outer parametric solution.

model.result().numerical(<ftag>).getElements() returns indices to columns in p of a simplex mesh.

model.result().numerical(<ftag>).getNData() returns the number of points in the data vector.

model.result().numerical(<ftag>).getCoordinates() returns the coordinates of the interpolation.

model.result().numerical(<ftag>).setInterpolationCoordinates(<value>) is identical to model.result().numerical(<ftag>).set(coord, <value>), when value is of type double[][].

The columns of the coord property are the coordinates for the evaluation points. If the number of rows in coord equals the space dimension, then coord are global coordinates, and the selection (or the property edim) determines the dimension in which the expressions are evaluated. For instance, dimension 2 means that the expressions are evaluated on boundaries in a 3D model. If the dimension to evaluate on is less than the space dimension, then the points in coord are projected onto the closest point on a domain of that dimension. It is further possible to select a single geometric entity of a given dimension. If so, then the closest point on that domain in the given dimension is used.

If the number of rows in coord is less than the space dimension, then these coordinates are parameter values on a geometry face or edge. In that case, the domain number for that face or edge must be specified in the selection.

name	Value	Default	Description
complexfun	on \| off	on	Use complex-valued functions with real input
const	String array of property/value pairs	Empty	Parameters to use in the expressions.
coord	double matrix	Empty	The coordinates to evaluate in. Datasets that define an interpolation in themselves, such as cut planes, revolve and so forth, can be evaluated directly in the coordinates that define their shapes, without specifying coord.
coorderr	on \| off	on	If on, evaluating for a set of points that all fall outside the geometry results in an error being reported.
data	none \| dataset name	First compatible dataset	The dataset this feature refers to.
differential	on \| off	on	Whether the expression should be linearized at the linearization point. Applicable only if evalmethod is harmonic.
edim	auto \| 0 \| 1 \| 2 \| 3	auto	Element dimension. This is used for arbitrary datasets. Solution datasets use selections as usual to specify where to perform the evaluation, and ignore the value of the edim property.
evalmethod	linpoint \| harmonic \| lintotal \| lintotalavg \| lintotalrms \| lintotalpeak	harmonic	Applicable only for solutions with a stored linearization point. Controls if the linearization point, the perturbation, or a combination should be used when evaluating the expression.
expr	String array	Model dependent	The expressions to evaluate.
ext	double between 0 and 1	0.1	Extrapolation distance: How much outside the mesh that the interpolation searches. The scale is in terms of the local element size.
matherr	on \| off	off	Error for undefined operation or variable
outersolnum	nonnegative integer	1	The index of the outer solutions to use. Applicable only for parametric sweep models.
phase	double	0	Evaluate solution at this angle, given in degrees.
refine	auto \| integer	auto	Refinement of elements for evaluation points.
recover	off \| pprint \| ppr	off	The derivative recovery method (off, within domains, or everywhere).
solnum	nonnegative integer array	All solutions	The solutions to use.
t	double array	Empty	The times to use. Available when the underlying solution is transient.
unit	String	Model dependent	The unit to use for the expression in expr. If the old unit is not valid when the expression changes, the unit property is reset to default.