Difference between revisions of "Main Page"

From Dirks Personal WiKi
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m (Test SyntaxHighlighter)
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[[File:Wikipedesketch.png|thumb|left|alt=A cartoon centipede reads books and types on a laptop.|The Wikipede edits ''[[wikipedia:Myriapoda]]''.]] This example is supposed to show how thumbnails can be made to display by default, as well as how inter-WiKi links work.
  
[[File:Wikipedesketch.png|thumb|left|alt=A cartoon centipede reads books and types on a laptop.|The Wikipede edits ''[[wikipedia:Myriapoda]]''.]] This example is supposed to show how thumbnails can be made to display by default, as well as how inter-WiKi links work.
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----
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The following is some code which has been suggested, to compute the reciprocal square root using a trick. It may not be helpful, because this code requires that the language implementation can already convert a floating-point number into its 64-bit representation.
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<syntaxhighlighter lang="cpp">
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/* Fast Inverse Square Root, using Matthew Robertson's
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* Magic Number for double-precision floating-point.
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*
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* Implemented August 2, 2024
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* by Dirk Mittler
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*
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*/
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#include <cstring>
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#include <cstdint>
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typedef double float64_t;
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float64_t Q_rsqrt(const float64_t number) noexcept {
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const float64_t threehalfs = 1.5;
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const float64_t halfnum = 0.5 * number;
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uint64_t temp;
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float64_t y;
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static_assert(sizeof(uint64_t) == sizeof(number),
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"`double` has a weird size.");
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memcpy(&temp, &number, sizeof(float64_t));
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// temp = 0x5f3759df - (temp >> 1); // Original 32-bit fr Quake III
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temp = 0x5FE6EB50C7B537A9 - (temp >> 1); // Matthew Robertson's
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memcpy(&y, &temp, sizeof(float64_t));
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y *= (threehalfs - (halfnum * y * y));
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y *= (threehalfs - (halfnum * y * y));
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y *= (threehalfs - (halfnum * y * y));
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return y * (threehalfs - (halfnum * y * y));
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}
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</syntaxhighlighter>

Revision as of 00:06, 31 August 2024

This is a personal MediaWiki.

The User's Guide will explain how to use the WiKi software, to Dirk.

Getting started

Eq 1 &em;&em; [math]\displaystyle{ y=\pm\sqrt{1-x^{2}} }[/math] &em;&em;&em;&em; (Equation for circle.)

Drop-Down Menu
  • [[Plastic Widgets]]
  • [[Framistans]]
  • [[Pet Rocks]]
  • Eq 1

The following is a hypothetical exercise...

A cartoon centipede reads books and types on a laptop.
The Wikipede edits wikipedia:Myriapoda.

This example is supposed to show how thumbnails can be made to display by default, as well as how inter-WiKi links work.

The following is some code which has been suggested, to compute the reciprocal square root using a trick. It may not be helpful, because this code requires that the language implementation can already convert a floating-point number into its 64-bit representation.

<syntaxhighlighter lang="cpp"> /* Fast Inverse Square Root, using Matthew Robertson's 

* Magic Number for double-precision floating-point.
* 
* Implemented August 2, 2024
* by Dirk Mittler
* 
*/
  1. include <cstring>
  2. include <cstdint>

typedef double float64_t;

float64_t Q_rsqrt(const float64_t number) noexcept { const float64_t threehalfs = 1.5; const float64_t halfnum = 0.5 * number; uint64_t temp; float64_t y; static_assert(sizeof(uint64_t) == sizeof(number), "`double` has a weird size."); memcpy(&temp, &number, sizeof(float64_t)); // temp = 0x5f3759df - (temp >> 1); // Original 32-bit fr Quake III temp = 0x5FE6EB50C7B537A9 - (temp >> 1); // Matthew Robertson's memcpy(&y, &temp, sizeof(float64_t)); y *= (threehalfs - (halfnum * y * y)); y *= (threehalfs - (halfnum * y * y)); y *= (threehalfs - (halfnum * y * y)); return y * (threehalfs - (halfnum * y * y)); }

</syntaxhighlighter>

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