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 // Copyright ©2019 The Gonum Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package mat_test import ( "fmt" "gonum.org/v1/gonum/blas/blas64" "gonum.org/v1/gonum/mat" ) // This example shows how simple user types can be constructed to // implement basic vector functionality within the mat package. func Example_userVectors() { // Perform the cross product of [1 2 3 4] and [1 2 3]. r := row{1, 2, 3, 4} c := column{1, 2, 3} var m mat.Dense m.Mul(c, r) fmt.Println(mat.Formatted(&m)) // Output: // // ⎡ 1 2 3 4⎤ // ⎢ 2 4 6 8⎥ // ⎣ 3 6 9 12⎦ } // row is a user-defined row vector. type row []float64 // Dims, At and T minimally satisfy the mat.Matrix interface. func (v row) Dims() (r, c int) { return 1, len(v) } func (v row) At(_, j int) float64 { return v[j] } func (v row) T() mat.Matrix { return column(v) } // RawVector allows fast path computation with the vector. func (v row) RawVector() blas64.Vector { return blas64.Vector{N: len(v), Data: v, Inc: 1} } // column is a user-defined column vector. type column []float64 // Dims, At and T minimally satisfy the mat.Matrix interface. func (v column) Dims() (r, c int) { return len(v), 1 } func (v column) At(i, _ int) float64 { return v[i] } func (v column) T() mat.Matrix { return row(v) } // RawVector allows fast path computation with the vector. func (v column) RawVector() blas64.Vector { return blas64.Vector{N: len(v), Data: v, Inc: 1} }