Native bindings and RBC vectors

The public Tcl procedures retain their argument parsing, aliases, help and existing list/dictionary result shapes. Numerical array conversion, allocation, evaluation loops and cleanup now run in C. SWIG is no longer required. The old SWIG pointer commands and internal array-conversion helpers have been removed.

RBC support is optional:

./configure --with-tcl=/path/to/tcl/lib --with-rbc=/path/to/rbc-tk9
make

--with-rbc accepts an RBC source tree, installed public-header directory, or installation prefix containing rbcVector.h, rbcDecls.h and rbcStubLib.c. The portable RBC stub client is compiled into tclinterp; the RBC shared library is not linked directly. Tcl 9 is required. A compatible rbc::vector package (version 0.5.0 or later) must be available at runtime for vector operations. List-only calls do not load RBC or Tk. Without --with-rbc, list operations work normally and vector requests return an explanatory error.

Every interpolation and approximation procedure accepts these additional options:

Option	Meaning
-input list	Default. All array arguments are Tcl lists.
-input vector	All array arguments are names of real RBC vectors. Scalar options remain scalar.
-output list	Default. Preserve existing list/dictionary results.
-output vector	Replace each numeric result list with its fully qualified RBC vector name.
-name name	Name of the primary yi output vector.
-names dictionary	Destination names for individual output fields (table below).
-ifexists error	Default. Reject existing vector or command names.
-ifexists replace	Update existing real RBC vectors; unrelated commands and complex destinations are rejected.

Input and output modes are independent: list-to-vector and vector-to-list calls are supported. Array inputs within a call use the same input mode. Omitted least-squares weights are generated internally, including in vector input mode. Vector index offsets do not affect sample alignment. Complex vectors and non-finite input samples/scalar parameters are rejected.

Relative vector names resolve in the public caller’s namespace. Destination namespaces must already exist. Omitted output names, or names equal to #auto, use RBC’s vector create #auto; each output gets a distinct name. New vectors have no mapped Tcl array variable. Returned vectors are caller-owned and survive the interpolation call; destroy them with ::rbc::vector destroy $name, or delete their namespace when appropriate.

package require tclinterp
namespace import ::tclinterp::interpolation::*

# Existing list interface remains unchanged.
set values [lin1d -x {0 1 2} -y {0 2 4} -xi {.5 1.5}]

# List input, automatically named vector output.
set result [lin1d -x {0 1 2} -y {0 2 4} -xi {.5 1.5} -output vector]
puts [$result index :]
::rbc::vector destroy $result

# Vector input and named output, resolved in this namespace.
package require rbc::vector
::rbc::vector create x y xi -variable {}
x set {0 1 2}
y set {0 2 4}
xi set {.5 1.5}
set result [lin1d -input vector -x x -y y -xi xi -output vector -name interpolated]

For multi-output operations, the returned dictionary has the same structure as in list mode. Unspecified fields receive automatic names. -name is shorthand for the yi entry of -names; supplying both for yi is an error.

Operation/options	Keys accepted by -names
Any single-result operation	yi
genBezier	xi, yi
least1d -coeffs	yi, coeffs.b, coeffs.c, coeffs.d
least1dDer	yi, yiDer
least1dDer -coeffs	yi, yiDer, coeffs.b, coeffs.c, coeffs.d
divDif1d -coeffs	yi, coeffs
cubicSpline1d -deriv	yi, yder1, yder2
hermiteSpline1d -deriv	yi, yder1

set result [cubicSpline1d -t {0 1 2} -y {0 1 4} -ti {.5 1.5} -deriv -output vector -names {yi fit yder1 slope yder2 curvature}]
puts [[dict get $result yder1] index :]

Unknown output keys and duplicate explicit destinations are rejected. Results are computed before publishing any output, so an input vector can also be a destination with -ifexists replace. Explicit destinations are checked before publication; new vectors are removed if a later publication step fails. Updates to existing vectors are not rolled back if application callbacks cause a publication error. Do not delete or replace destinations from notification callbacks during publication.

The C binding validates sizes, lengths, required knot ordering, distinct polynomial abscissas, least-squares weights and boundary conditions before entering the legacy numerical routines. Linear/spline operations need at least two knots; not-a-knot cubic boundaries require at least four. Degree-zero Bezier curves are supported. The native boundary also fixes the right-only not-a-knot boundary selection in the underlying cubic routine. The numerical kernels still use their existing algorithms.

Run tests using make test with argparse, Tcllib and (for vector tests) rbc::vector on TCLLIBPATH. No display server or Tk initialization is required for vector tests.

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Copyright (c) George Yashin