scs

Racket bindings for SCS, the Splitting Conic Solver, built with Nix. SCS solves convex cone programs of the form

minimize    (1/2) xᵀP x + cᵀx
subject to  A x + s = b,  s ∈ K

where K is a Cartesian product of zero, positive-orthant, box, second-order, semidefinite, exponential, and power cones.

The default API is high level:

#lang racket

(require scs)

;; minimize (1/2) xᵀP x + cᵀx
;;   s.t.  -x0 + x1 = -1,  x0 <= 0.3,  x1 <= -0.5
(define A
  (scs:matrix 3 2
              -1 1
               1 0
               0 1))

(define P
  (scs:sparse-matrix 2 2
                     '(0 0 3)
                     '(0 1 -1)
                     '(1 1 2)))

(define result
  (solve #:A A
         #:b #(-1.0 0.3 -0.5)
         #:c #(-1.0 -1.0)
         #:P P
         #:cone (make-cone #:zero 1 #:positive 2)))

(scs-result-status result)   ; => "solved"
(scs-result-x result)        ; => #(0.3 -0.7)

Use (require scs/foreign) for the contracted low-level wrappers, and (require scs/foreign/raw) for the direct C FFI bindings.

Full documentation — a Guide, worked Examples, and an API Reference — is in the package's Scribble docs (scs/scribblings/, hosted on docs.racket-lang.org); render them locally with raco scribble scs/scribblings/scs.scrbl or raco docs scs.

Quick start

nix build              # build, run tests + examples
nix develop            # dev shell: racket + scs + python(scs) + linters
racket scs/examples/test/01-linear-program.rkt

Layout

• scs/main.rkt — high-level root API for (require scs).
• scs/foreign.rkt — contracted low-level Racket wrappers.
• scs/foreign/raw.rkt — direct C FFI bindings to the SCS C API.
• scs/core/ — high-level implementation: matrix, cone, settings, solve.
• scs/private/install-scs-native.rkt — native-library pre-install hook.
• scs/examples/ — numbered literate (#lang scribble/lp2) examples woven into the docs; each provides run-example. Companion runners/tests live in scs/examples/test/.
• flake.nix — Nix build; uses nixpkgs#scs (3.2.11, both solver variants, LAPACK).

See AGENTS.md for architecture notes.