101 lines
2.3 KiB
Markdown
101 lines
2.3 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 Mask
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> High word mask for the 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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<!-- eslint-disable id-length -->
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```javascript
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var FLOAT64_HIGH_WORD_EXPONENT_MASK = require( '@stdlib/constants/float64/high-word-exponent-mask' );
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```
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#### FLOAT64_HIGH_WORD_EXPONENT_MASK
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High word mask for the exponent of a [double-precision floating-point number][ieee754].
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<!-- eslint-disable id-length -->
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```javascript
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// 0x7ff00000 = 2146435072 => 0 11111111111 00000000000000000000
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var bool = ( FLOAT64_HIGH_WORD_EXPONENT_MASK === 0x7ff00000 );
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// returns true
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- The higher order word of a [double-precision floating-point number][ieee754] is a 32-bit integer containing the more significant bits which include the exponent and sign.
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint-disable id-length -->
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<!-- eslint no-undef: "error" -->
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```javascript
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var getHighWord = require( '@stdlib/number/float64/base/get-high-word' );
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var FLOAT64_HIGH_WORD_EXPONENT_MASK = require( '@stdlib/constants/float64/high-word-exponent-mask' );
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var out;
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var hi;
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var x;
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x = 11.5;
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hi = getHighWord( x ); // => 0 10000000010 01110000000000000000
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// returns 1076297728
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// Mask off all bits except for the exponent bits:
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out = hi & FLOAT64_HIGH_WORD_EXPONENT_MASK; // => 0 10000000010 00000000000000000000
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// returns 1075838976
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// Mask on the exponent bits and leave other bits unchanged:
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out = hi | FLOAT64_HIGH_WORD_EXPONENT_MASK; // => 0 11111111111 01110000000000000000
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// returns 2146893824
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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]: http://en.wikipedia.org/wiki/IEEE_754-1985
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</section>
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<!-- /.links -->
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