Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 | 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 26x 26x 26x 26x 26x 26x 26x 2x 2x 24x 24x 24x 24x 24x 26x 24x 26x 12x 12x 18x 18x 48x 6x 6x 42x 42x 12x 12x 12x 12x 12x 30x 30x 54x 6x 6x 48x 48x 24x 24x 12x 12x 12x 26x 3x 3x 3x 3x 3x | /**
* @license Apache-2.0
*
* Copyright (c) 2025 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict';
// MODULES //
var isRowMajor = require( '@stdlib/ndarray/base/assert/is-row-major' );
// MAIN //
/**
* Finds the index of the last non zero column in a matrix `A`.
*
* @private
* @param {PositiveInteger} M - number of rows in `A`
* @param {PositiveInteger} N - number of columns in `A`
* @param {Float64Array} A - input matrix
* @param {integer} strideA1 - stride of the first dimension of `A`
* @param {integer} strideA2 - stride of the second dimension of `A`
* @param {NonNegativeInteger} offsetA - index offset for `A`
* @returns {integer} index of the last non zero column
*
* @example
* var Float64array = require( '@stdlib/array/float64' );
*
* var A = new Float64array( [ 1.0, 2.0, 0.0, 3.0, 4.0, 0.0 ] ); // => [ [ 1.0, 2.0, 0.0 ], [ 3.0, 4.0, 0.0 ] ]
*
* var out = iladlc( 2, 3, A, 3, 1, 0 );
* // returns 1
*/
function iladlc( M, N, A, strideA1, strideA2, offsetA ) {
var ia1;
var ia2;
var i;
var j;
if ( M === 0 || N === 0 ) {
return -1; // Invalid index
}
ia1 = offsetA + ( (N-1) * strideA2 ); // A( 1, N )
ia2 = ia1 + ( (M-1) * strideA1 ); // A( M, N )
// Quick test for common case where corners are non-zero:
if ( A[ ia1 ] !== 0.0 || A[ ia2 ] !== 0.0 ) {
return N - 1;
}
if ( isRowMajor( [ strideA1, strideA2 ] ) ) {
ia1 = offsetA;
for ( i = 0; i < M; i++ ) {
ia2 = ( N - 1 ) * strideA2;
for ( j = N-1; j >= 0; j-- ) {
if ( A[ ia1 + ia2 ] !== 0.0 ) {
return j;
}
ia2 -= strideA2;
}
ia1 += strideA1;
}
} else {
ia1 = offsetA + ( (N-1) * strideA2 );
for ( i = N-1; i >= 0; i-- ) {
ia2 = 0;
for ( j = 0; j < M; j++ ) {
if ( A[ ia1 + ia2 ] !== 0.0 ) {
return i;
}
ia2 += strideA1;
}
ia1 -= strideA2;
}
}
return -1;
}
// EXPORTS //
module.exports = iladlc;
|