COMSOL Multiphysics™

geomspline
Purpose
geomspline
Spline interpolation.
Syntax
Description
c = geomspline(p,...)
c = geomspline(p,...) creates a curve2 or curve3 object from point data p by
spline interpolation. The object generated is a closed or open, C 1 or C 2 continuous,
spline.
p is a 2-by-np (in 2D) or 3-by-np (in 3D) matrix that specifies interpolation points.
The function geomspline accepts the following property/value pairs:
TABLE 1-69: VALID PROPERTY/VALUE PAIRS
PROPERTY NAME PROPERTY VALUE DEFAULT DESCRIPTION
Closed auto | on | off auto Closed or open curve
SplineDir 2-by-np matrix
3-by-np matrix
SplineMethod uniform |
chordlength |
centripetal |
foley
chordlength
Tangent vectors for the
corresponding points in p
Method for global
parameterization
The property SplineDir is used to specify a tangent vector for the corresponding
point in p. This means that the first control point is given and the curve thus
generated is only guaranteed to be C 1 (continuous first derivatives). If this property
is not given, however, the curve generated is guaranteed to be C 2 (continuous
second derivatives). The SplineMethod property does not affect the curve if the
SplineDir property is used.
The property SplineMethod controls the method for how to compute the global
parameterization of the curve. The global parameterization is a parameter that varies
from 0 to 1, from the first interpolated point to the last. For a closed curve the last
point is equivalent to the first. The value uniform means that the global
parameterization is [0, 1,..., np]/np. The default value chordlength means
that the global parameterization is [0, norm(p(:,2)-p(:,1)),
norm(p(:,3)-p(:,2)),..., norm(p(:,np)-p(:,np-1))]/
sum(sqrt(sum((diff(p')').^2)')), where the denominator is the total chord
length. The values centripetal and foley are two additional methods that handle
irregular point sets p more effectively.
The property Closed controls the closure of the spline. If Closed is on the first
point is regarded as the last point. The value auto for the property Closed generates
a closed curve whenever the first and last points in a scaled version of the point set
238 | CHAPTER 1: COMMAND REFERENCE