97 lines
2.0 KiB
Markdown
97 lines
2.0 KiB
Markdown
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# Exponent
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> Return an integer corresponding to the unbiased exponent of a [double-precision floating-point number][ieee754].
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<section class="usage">
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## Usage
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```javascript
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var exponent = require( '@stdlib/number/float64/base/exponent' );
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```
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#### exponent( x )
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Returns an `integer` corresponding to the unbiased exponent of a [double-precision floating-point number][ieee754].
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```javascript
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var exp = exponent( 3.14e307 ); // => 2**1021 ~ 1e307
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// returns 1021
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exp = exponent( 3.14e-307 ); // => 2**-1019 ~ 1e-307
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// returns -1019
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exp = exponent( -3.14 );
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// returns 1
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exp = exponent( 0.0 );
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// returns -1023
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exp = exponent( NaN );
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// returns 1024
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var randu = require( '@stdlib/random/base/randu' );
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var round = require( '@stdlib/math/base/special/round' );
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var pow = require( '@stdlib/math/base/special/pow' );
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var exponent = require( '@stdlib/number/float64/base/exponent' );
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var frac;
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var exp;
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var x;
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var e;
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var i;
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// Generate random numbers and extract their exponents...
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for ( i = 0; i < 100; i++ ) {
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frac = randu() * 10.0;
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exp = round( randu()*646.0 ) - 323;
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x = frac * pow( 10.0, exp );
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e = exponent( x );
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console.log( 'x: %d. unbiased exponent: %d.', x, e );
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}
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[ieee754]: https://en.wikipedia.org/wiki/IEEE_754-1985
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</section>
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<!-- /.links -->
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