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Overview
| Comment: | Tweaks to the floatingpoint.html page. |
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dcd828be81b3efebde3bab827a13427d |
| User & Date: | drh 2020-07-15 15:03:46 |
Context
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2020-07-18
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| 16:35 | Documentation for UPDATE FROM. (check-in: ba3810c515 user: drh tags: trunk) | |
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2020-07-17
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| 17:35 | Revise syntax diagrams to include the FROM clause on UPDATE statements. (Closed-Leaf check-in: bd9cdee968 user: drh tags: update-from) | |
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2020-07-15
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| 15:03 | Tweaks to the floatingpoint.html page. (check-in: dcd828be81 user: drh tags: trunk) | |
| 01:43 | Merge fixes from the 3.32 branch. (check-in: bd3dff05f9 user: drh tags: trunk) | |
Changes
Changes to pages/floatingpoint.in.
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</b></blockquote> <p>If you remember nothing else about floating-point values, please don't forget this one key idea. <h3>Is it close enough?</h3> <p>15 significant digits of precision are sufficient for most computations. For example, if "47.49" represents a price and inflation is running at 2% per year, then the price is going up by about 0.0000000301 dollars per second. The error in the recorded value of 47.49 represents about 65 nanoseconds worth of inflation. So if 47.49 price is exact when you enter it, then the effects of inflation will cause the value actually stored (47.4900000000000019895196601282805204391479492187) to be exact about 65 nanoseconds later. Surely that level of precision is sufficient for most purposes? <h1>Extensions For Dealing With Floating Point Numbers</h1> <tcl>hd_fragment ieee754ext {ieee754 extension}</tcl> <h2>The ieee754.c Extension</h2> |
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</b></blockquote> <p>If you remember nothing else about floating-point values, please don't forget this one key idea. <h3>Is it close enough?</h3> <p>The precision provided by IEEE 754 Binary64 is sufficient for most computations. For example, if "47.49" represents a price and inflation is running at 2% per year, then the price is going up by about 0.0000000301 dollars per second. The error in the recorded value of 47.49 represents about 66 nanoseconds worth of inflation. So if the 47.49 price is exact when you enter it, then the effects of inflation will cause the value actually stored (47.4900000000000019895196601282805204391479492187) to be exact less than one ten-millionth of a second later. Surely that level of precision is sufficient for most purposes? <h1>Extensions For Dealing With Floating Point Numbers</h1> <tcl>hd_fragment ieee754ext {ieee754 extension}</tcl> <h2>The ieee754.c Extension</h2> |