CFD Utilities Files

The interp2d collection offers a modest choice of methods for interpolating
bivariate data, where smoothness in the data is likely to be assumed.  Some
of the methods require structured data; a few handle irregular data.  These
all precede the ADT-based (alternating digital tree) methods that are now
likely to be preferable for structured, triangulated, or mixed-cell surface
data.

The handful of smoothing methods here are early and questionable, since
their 1-D analogues would not be considered good approaches.  The Kriging-
type method of the Optimal_Interpolation package (see also program ANCHOR)
is likely to be preferable for dealing with noisy data in two or more
dimensions.

See program SMOOTH2D for driving many of the methods listed below.  Some
of the now-deprecated methods are retained to avoid suppressing them in
SMOOTH2D.

Some intersection utiities are also included in this collection.
For instance, INTSEC2D uses 2-space ADT searching and 1-variable uncon-
strained no-derivative minimization to intersect a one-piece curve with
a J boundary of a 2D structured multiblock volume grid.

akima.f      Early interpolation of scattered 2-space data by triangulation
bicubmat.f   Lower-level matrix set-up routine used by LCSFIT2D & PLBICUBE
bilinear.f   Bilinear analogue of the bicubic LCSFIT2D for regular data
bilint.f     Part of the RIPPLE2D approach to searching a structured grid
bilintp.f    Variant of BILINT for an (x, y) grid stored as pairs
bvlsq.f      Linear least sqrs. fit of user basis fns. to scattered data
facets.f     Early bilinear interpolation of scattered data
hardy.f      Interpoln. via linear combination of distance-type basis fns.
inmesh.f     Early logical function for searching a 2-space structured mesh
intsec2.f    Intersection of 2 discretized curves in 2-space
intsec2d.f90 Intersection of a 2-space multiblock curve and one-piece curve
intsec2t.f   Variant of INTSEC2: also returns intersection arc length Ts
intsec3.f    Intersection of B-spline curve and discretized curve in 2-spc.
lcsfit2d.f   Nonparametric bicubic local spline interpoln. on regular grid
lcsint2d.f   Specialized 2-space interpoln. within data rows by 1-D LCSFIT
lint2d.f     Bilinear interpolation within a rectangular table
nearpt.f     Lower-level utility employed by FACETS
pbilint.f    Parametric bilinear interp. within regular 3-sp. surface mesh
pbvlsq.f     Bivariate polynomial linear least squares fit, scattered data
plbicube.f   Parametric local bicubic interpolation of an (x,y,z) surface
plincub.f    Var. of PBILINT: linear in one (u,v) dirn.; cubic in the other
plsint2d.f   Variant of LCSINT2D suited to rounded airfoil leading edges
plstangent.f Find arc length t for given dy/dx on a discretized (x,y) curve
plxcut.f     Find arc length t for given   x   on a discretized (x,y) curve
smooth2d.f   Iterative smoothing of f(u,v) on a structured (x,y,z) surface
table2.f     Bilinear interpolation within a rectangular table, in fn. form
tfif2d.f     Variant of TFI2D (gridlib) handles additional function data
tpspln.f     Thin plate spline var. of HARDY method: log-based basis fns.