README.md

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gindexOfColumn

Return the index of the first column in an input matrix which has the same elements as a provided search vector.

Usage

import gindexOfColumn from 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-ext-base-gindex-of-column@deno/mod.js';

You can also import the following named exports from the package:

import { ndarray } from 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-ext-base-gindex-of-column@deno/mod.js';

gindexOfColumn( order, M, N, A, LDA, x, strideX )

Returns the index of the first column in an input matrix which has the same elements as a provided search vector.

/*
    A = [
        [ 1.0, 2.0 ],
        [ 3.0, 4.0 ],
        [ 0.0, 0.0 ]
    ]
*/
var A = [ 1.0, 2.0, 3.0, 4.0, 0.0, 0.0 ];

var x = [ 2.0, 4.0, 0.0 ];
var out = gindexOfColumn( 'row-major', 3, 2, A, 2, x, 1 );
// returns 1

The function has the following parameters:

• order: storage layout.
• M: number of rows in A.
• N: number of columns in A.
• A: input matrix as a linear array.
• LDA: stride of the first dimension of A (a.k.a., leading dimension of the matrix A).
• x: search vector.
• strideX: stride length of x.

If the function is unable to find a matching column, the function returns -1.

var A = [ 1.0, 2.0, 3.0, 4.0, 0.0, 0.0 ];

var x = [ -2.0, -4.0, 0.0 ];
var out = gindexOfColumn( 'row-major', 3, 2, A, 2, x, 1 );
// returns -1

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';

// Initial arrays:
var A0 = new Float64Array( [ 9999.0, 1.0, 2.0, 3.0, 4.0, 0.0, 0.0 ] );
var x0 = new Float64Array( [ 9999.0, 2.0, 4.0, 0.0 ] );

// Create offset views:
var A1 = new Float64Array( A0.buffer, A0.BYTES_PER_ELEMENT*1 ); // start at 2nd element
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

var out = gindexOfColumn( 'row-major', 3, 2, A1, 2, x1, 1 );
// returns 1

gindexOfColumn.ndarray( M, N, A, strideA1, strideA2, offsetA, x, strideX, offsetX )

Returns the index of the first column in an input matrix which has the same elements as a provided search vector using alternative indexing semantics.

/*
    A = [
        [ 1.0, 2.0 ],
        [ 3.0, 4.0 ],
        [ 0.0, 0.0 ]
    ]
*/
var A = [ 1.0, 2.0, 3.0, 4.0, 0.0, 0.0 ];

var x = [ 2.0, 4.0, 0.0 ];
var out = gindexOfColumn.ndarray( 3, 2, A, 2, 1, 0, x, 1, 0 );
// returns 1

The function has the following parameters:

• M: number of rows in A.
• N: number of columns in A.
• A: input matrix as a linear array.
• strideA1: stride of the first dimension of A.
• strideA2: stride of the second dimension of A.
• offsetA: starting index for A.
• x: search vector.
• strideX: stride length of x.
• offsetX: starting index for x.

While typed array views mandate a view offset based on the underlying buffer, offset parameters support indexing semantics based on starting indices. For example,

/*
    A = [
        [ 1.0, 2.0 ],
        [ 3.0, 4.0 ],
        [ 0.0, 0.0 ]
    ]
*/
var A = [ 9999.0, 1.0, 2.0, 3.0, 4.0, 0.0, 0.0 ];

var x = [ 9999.0, 2.0, 4.0, 0.0 ];
var out = gindexOfColumn.ndarray( 3, 2, A, 2, 1, 1, x, 1, 1 );
// returns 1

Notes

• When searching for a matching column, the function checks for equality using the strict equality operator ===. As a consequence, NaN values are considered distinct, and -0 and +0 are considered the same.
• Both functions support array-like objects having getter and setter accessors for array element access (e.g., @stdlib/array-base/accessor).

Examples

import ndarray2array from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-to-array@deno/mod.js';
import shape2strides from 'https://cdn.jsdelivr.net/gh/stdlib-js/ndarray-base-shape2strides@deno/mod.js';
import gindexOfColumn from 'https://cdn.jsdelivr.net/gh/stdlib-js/blas-ext-base-gindex-of-column@deno/mod.js';

var shape = [ 3, 3 ];
var order = 'row-major';
var strides = shape2strides( shape, order );

var A = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0 ];
console.log( ndarray2array( A, shape, strides, 0, order ) );

var x = [ 2.0, 5.0, 8.0 ];
console.log( x );

var out = gindexOfColumn( order, shape[ 0 ], shape[ 1 ], A, strides[ 0 ], x, 1, 0 );
console.log( out );

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Notice

This package is part of stdlib, a standard library with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2026. The Stdlib Authors.