gonum.org/v1/gonum v0.17.0: mat.Solve

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify gonum.org/v1/gonum/mat.Solve in pkg:golang/gonum.org/v1/gonum@v0.17.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/gonum.org/v1/gonum@v0.17.0
Demonstrate these symbols/APIs:
  - gonum.org/v1/gonum/mat.Solve

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:55d02db2b509ed3f755ed32718588eb2c68365d62bd45810e2c168e2643a1730","contract":["mat.Dense.Solve solves a linear system of equations A * X = B for square matrices","mat.Dense.Solve returns an error when the coefficient matrix is singular","mat.Dense.Solve panics with ErrShape when matrix dimensions do not match","mat.VecDense.SolveVec solves a linear system A * x = b for a vector right-hand side","mat.VecDense.SolveVec panics with ErrShape when vector dimensions do not match"],"goal":"verify gonum.org/v1/gonum/mat.Solve in pkg:golang/gonum.org/v1/gonum@v0.17.0","kind":"HOW","packages":["pkg:golang/gonum.org/v1/gonum@v0.17.0"],"schemaVersion":1,"symbols":["gonum.org/v1/gonum/mat.Solve"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/gonum.org/v1/gonum@v0.17.0"],"schemaVersion":1,"subject":"pkg:golang/gonum.org/v1/gonum@v0.17.0","symbols":["gonum.org/v1/gonum/mat.Solve"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require gonum.org/v1/gonum v0.17.0

gonum.org/v1/gonum v0.17.0 h1:VbpOemQlsSMrYmn7T2OUvQ4dqxQXU+ouZFQsZOx50z4=
gonum.org/v1/gonum v0.17.0/go.mod h1:El3tOrEuMpv2UdMrbNlKEh9vd86bmQ6vqIcDwxEOc1E=

package main

import (
	"fmt"

	"gonum.org/v1/gonum/mat"
)

func main() {
	// Solve linear system A * X = B
	// [ 2  1 ] [ x0 ] = [ 5 ]
	// [ 1  3 ] [ x1 ]   [ 10 ]
	a := mat.NewDense(2, 2, []float64{
		2, 1,
		1, 3,
	})
	b := mat.NewDense(2, 1, []float64{
		5,
		10,
	})

	var x mat.Dense
	if err := x.Solve(a, b); err != nil {
		fmt.Printf("Solve failed: %v\n", err)
		return
	}

	fmt.Printf("Solution: x0 = %.1f, x1 = %.1f\n", x.At(0, 0), x.At(1, 0))

	// Solve linear system A * x = b for vector right-hand side
	bVec := mat.NewVecDense(2, []float64{5, 10})
	var xVec mat.VecDense
	if err := xVec.SolveVec(a, bVec); err != nil {
		fmt.Printf("SolveVec failed: %v\n", err)
		return
	}
	fmt.Printf("Vector Solution: x0 = %.1f, x1 = %.1f\n", xVec.AtVec(0), xVec.AtVec(1))
}

{
  "schemaVersion": 1,
  "goal": "verify gonum.org/v1/gonum/mat.Solve in pkg:golang/gonum.org/v1/gonum@v0.17.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/gonum.org/v1/gonum@v0.17.0"
  ],
  "symbols": [
    "gonum.org/v1/gonum/mat.Solve"
  ]
}

package main

import (
	"fmt"
	"math"
	"os"

	"gonum.org/v1/gonum/mat"
)

func main() {
	// Assertion 1: mat.Dense.Solve solves a linear system of equations A * X = B for square matrices
	a := mat.NewDense(2, 2, []float64{
		2, 1,
		1, 3,
	})
	b := mat.NewDense(2, 1, []float64{
		5,
		10,
	})
	var x mat.Dense
	if err := x.Solve(a, b); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unexpected error solving system: %v\n", err)
		os.Exit(1)
	}
	r, c := x.Dims()
	if r != 2 || c != 1 {
		fmt.Fprintf(os.Stderr, "FAIL: expected dimensions (2, 1), got (%d, %d)\n", r, c)
		os.Exit(1)
	}
	if math.Abs(x.At(0, 0)-1.0) > 1e-9 || math.Abs(x.At(1, 0)-3.0) > 1e-9 {
		fmt.Fprintf(os.Stderr, "FAIL: unexpected solution values: got (%f, %f), want (1.0, 3.0)\n", x.At(0, 0), x.At(1, 0))
		os.Exit(1)
	}

	// Assertion 2: mat.Dense.Solve returns an error when the coefficient matrix is singular
	singular := mat.NewDense(2, 2, []float64{
		1, 2,
		2, 4,
	})
	var xSingular mat.Dense
	if err := xSingular.Solve(singular, b); err == nil {
		fmt.Fprintf(os.Stderr, "FAIL: expected error for singular matrix, got nil\n")
		os.Exit(1)
	}

	// Assertion 3: mat.Dense.Solve panics with ErrShape when matrix dimensions do not match
	panickedShapeDense := false
	func() {
		defer func() {
			if r := recover(); r != nil {
				panickedShapeDense = true
			}
		}()
		badB := mat.NewDense(3, 1, []float64{1, 2, 3})
		var badX mat.Dense
		_ = badX.Solve(a, badB)
	}()
	if !panickedShapeDense {
		fmt.Fprintf(os.Stderr, "FAIL: expected panic on matrix dimension mismatch\n")
		os.Exit(1)
	}

	// Assertion 4: mat.VecDense.SolveVec solves a linear system A * x = b for a vector right-hand side
	bVec := mat.NewVecDense(2, []float64{5, 10})
	var xVec mat.VecDense
	if err := xVec.SolveVec(a, bVec); err != nil {
		fmt.Fprintf(os.Stderr, "FAIL: unexpected error in SolveVec: %v\n", err)
		os.Exit(1)
	}
	if xVec.Len() != 2 {
		fmt.Fprintf(os.Stderr, "FAIL: expected vector length 2, got %d\n", xVec.Len())
		os.Exit(1)
	}
	if math.Abs(xVec.AtVec(0)-1.0) > 1e-9 || math.Abs(xVec.AtVec(1)-3.0) > 1e-9 {
		fmt.Fprintf(os.Stderr, "FAIL: unexpected SolveVec values: got (%f, %f), want (1.0, 3.0)\n", xVec.AtVec(0), xVec.AtVec(1))
		os.Exit(1)
	}

	// Assertion 5: mat.VecDense.SolveVec panics with ErrShape when vector dimensions do not match
	panickedShapeVec := false
	func() {
		defer func() {
			if r := recover(); r != nil {
				panickedShapeVec = true
			}
		}()
		badBVec := mat.NewVecDense(3, []float64{1, 2, 3})
		var badXVec mat.VecDense
		_ = badXVec.SolveVec(a, badBVec)
	}()
	if !panickedShapeVec {
		fmt.Fprintf(os.Stderr, "FAIL: expected panic on vector dimension mismatch\n")
		os.Exit(1)
	}

	fmt.Println("All gonum mat.Solve contract assertions passed.")
}