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@@ -0,0 +1,128 @@
<!--

@license Apache-2.0

Copyright (c) 2026 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.

-->

# dfirstIndexGreaterThan

> Return the index of the first element in a one-dimensional double-precision floating-point ndarray which is greater than a corresponding element in another one-dimensional double-precision floating-point ndarray.

<section class="intro">

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var dfirstIndexGreaterThan = require( '@stdlib/blas/ext/base/ndarray/dfirst-index-greater-than' );
```

#### dfirstIndexGreaterThan( arrays )

Returns the index of the first element in a one-dimensional double-precision floating-point ndarray which is greater than a corresponding element in another one-dimensional double-precision floating-point ndarray.

```javascript
var Float64Vector = require( '@stdlib/ndarray/vector/float64' );

var x = new Float64Vector( [ 0.0, 0.0, 1.0, 0.0 ] );
var y = new Float64Vector( [ 0.0, 0.0, 0.0, 0.0 ] );

var idx = dfirstIndexGreaterThan( [ x, y ] );
// returns 2
```

The function has the following parameters:

- **arrays**: array-like object containing the following ndarrays:

- first one-dimensional input ndarray.
- second one-dimensional input ndarray.

If the function is unable to find an element in the first one-dimensional input ndarray which is greater than a corresponding element in the second one-dimensional input ndarray, the function returns `-1`.

```javascript
var Float64Vector = require( '@stdlib/ndarray/vector/float64' );

var x = new Float64Vector( [ 1.0, 2.0, 3.0, 4.0 ] );
var y = new Float64Vector( [ 5.0, 6.0, 7.0, 8.0 ] );

var idx = dfirstIndexGreaterThan( [ x, y ] );
// returns -1
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

- When comparing elements, the function checks whether an element in the first one-dimensional input ndarray is greater than a corresponding element in the second one-dimensional input ndarray using the greater-than operator `>`. As a consequence, comparisons involving `NaN` always evaluate to `false`.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var discreteUniform = require( '@stdlib/random/discrete-uniform' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var dfirstIndexGreaterThan = require( '@stdlib/blas/ext/base/ndarray/dfirst-index-greater-than' );

var opts = {
'dtype': 'float64'
};
var x = discreteUniform( [ 10 ], 0, 10, opts );
console.log( ndarray2array( x ) );

var y = discreteUniform( [ 10 ], 0, 10, opts );
console.log( ndarray2array( y ) );

var idx = dfirstIndexGreaterThan( [ x, y ] );
console.log( idx );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

</section>

<!-- /.links -->
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/**
* @license Apache-2.0
*
* Copyright (c) 2026 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 bench = require( '@stdlib/bench' );
var isInteger = require( '@stdlib/assert/is-integer' ).isPrimitive;
var pow = require( '@stdlib/math/base/special/pow' );
var Float64Vector = require( '@stdlib/ndarray/vector/float64' );
var ones = require( '@stdlib/array/ones' );
var format = require( '@stdlib/string/format' );
var pkg = require( './../package.json' ).name;
var dfirstIndexGreaterThan = require( './../lib' );


// VARIABLES //

var options = {
'dtype': 'float64'
};


// FUNCTIONS //

/**
* Creates a benchmark function.
*
* @private
* @param {PositiveInteger} len - array length
* @returns {Function} benchmark function
*/
function createBenchmark( len ) {
var x = new Float64Vector( ones( len, options.dtype ) );
var y = new Float64Vector( ones( len, options.dtype ) );
return benchmark;

/**
* Benchmark function.
*
* @private
* @param {Benchmark} b - benchmark instance
*/
function benchmark( b ) {
var out;
var i;

b.tic();
for ( i = 0; i < b.iterations; i++ ) {
out = dfirstIndexGreaterThan( [ x, y ] );
if ( out !== out ) {
b.fail( 'should return an integer' );
}
}
b.toc();
if ( !isInteger( out ) ) {
b.fail( 'should return an integer' );
}
b.pass( 'benchmark finished' );
b.end();
}
}


// MAIN //

/**
* Main execution sequence.
*
* @private
*/
function main() {
var len;
var min;
var max;
var f;
var i;

min = 1; // 10^min
max = 6; // 10^max

for ( i = min; i <= max; i++ ) {
len = pow( 10, i );
f = createBenchmark( len );
bench( format( '%s:len=%d', pkg, len ), f );
}
}

main();
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{{alias}}( arrays )
Returns the index of the first element in a one-dimensional double-
precision floating-point ndarray which is greater than a corresponding
element in another one-dimensional double-precision floating-point ndarray.

When comparing elements, the function checks whether an element in the
first one-dimensional input ndarray is greater than a corresponding element
in the second one-dimensional input ndarray using the greater-than operator
`>`. As a consequence, comparisons involving `NaN` always evaluate to
`false`.

Parameters
----------
arrays: ArrayLikeObject<ndarray>
Array-like object containing the following ndarrays:

- first one-dimensional input ndarray.
- second one-dimensional input ndarray.

Returns
-------
out: integer
Index.

Examples
--------
> var x = new {{alias:@stdlib/ndarray/vector/float64}}( [ 0.0, 0.0, 1.0, 0.0 ] );
> var y = new {{alias:@stdlib/ndarray/vector/float64}}( [ 0.0, 0.0, 0.0, 0.0 ] );
> {{alias}}( [ x, y ] )
2

See Also
--------
Original file line number Diff line number Diff line change
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/*
* @license Apache-2.0
*
* Copyright (c) 2026 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.
*/

// TypeScript Version: 4.1

/// <reference types="@stdlib/types"/>

import { float64ndarray } from '@stdlib/types/ndarray';

/**
* Returns the index of the first element in a one-dimensional double-precision floating-point ndarray which is greater than a corresponding element in another one-dimensional double-precision floating-point ndarray.
*
* ## Notes
*
* - The function expects the following ndarrays:
*
* - first one-dimensional input ndarray.
* - second one-dimensional input ndarray.
*
* - When comparing elements, the function checks whether an element in the first one-dimensional input ndarray is greater than a corresponding element in the second one-dimensional input ndarray using the greater-than operator `>`. As a consequence, comparisons involving `NaN` always evaluate to `false`.
*
* @param arrays - array-like object containing ndarrays
* @returns index
*
* @example
* var Float64Vector = require( '@stdlib/ndarray/vector/float64' );
*
* var x = new Float64Vector( [ 0.0, 0.0, 1.0, 0.0 ] );
* var y = new Float64Vector( [ 0.0, 0.0, 0.0, 0.0 ] );
*
* var idx = dfirstIndexGreaterThan( [ x, y ] );
* // returns 2
*/
declare function dfirstIndexGreaterThan( arrays: [ float64ndarray, float64ndarray ] ): number;


// EXPORTS //

export = dfirstIndexGreaterThan;
Original file line number Diff line number Diff line change
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/*
* @license Apache-2.0
*
* Copyright (c) 2026 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.
*/

/* eslint-disable space-in-parens */

import zeros = require( '@stdlib/ndarray/zeros' );
import dfirstIndexGreaterThan = require( './index' );


// TESTS //

// The function returns a number...
{
const x = zeros( [ 10 ], {
'dtype': 'float64'
});
const y = zeros( [ 10 ], {
'dtype': 'float64'
});

dfirstIndexGreaterThan( [ x, y ] ); // $ExpectType number
}

// The compiler throws an error if the function is provided a first argument which is not an array of ndarrays...
{
dfirstIndexGreaterThan( '10' ); // $ExpectError
dfirstIndexGreaterThan( 10 ); // $ExpectError
dfirstIndexGreaterThan( true ); // $ExpectError
dfirstIndexGreaterThan( false ); // $ExpectError
dfirstIndexGreaterThan( null ); // $ExpectError
dfirstIndexGreaterThan( undefined ); // $ExpectError
dfirstIndexGreaterThan( [] ); // $ExpectError
dfirstIndexGreaterThan( {} ); // $ExpectError
dfirstIndexGreaterThan( ( x: number ): number => x ); // $ExpectError
}

// The compiler throws an error if the function is provided an unsupported number of arguments...
{
const x = zeros( [ 10 ], {
'dtype': 'float64'
});
const y = zeros( [ 10 ], {
'dtype': 'float64'
});

dfirstIndexGreaterThan(); // $ExpectError
dfirstIndexGreaterThan( [ x, y ], {} ); // $ExpectError
}
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