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User talk:Retroburrowers: Difference between revisions
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(sorry can´t test. out of memory) |
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false positives due to lack of precision. Please test the beta on fuse, and post your versions after
not having a Next w/1.5 MB ram.
--Frisian wrote:
A little info why your programs did not give results.
<lang zxbasic> 5 FOR r=34 TO 5 STEP -1
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</lang>
This code will not run on ZX Spectrum nor on Fuse. In line 5 the last dim statement uses to much memory 249*249*5 = 310005 Bytes,
this is even more then the total amount of memory for a ZX Spectrum 128. Therefore it´s not a ZX Spectrum program. Also it has the
Please check [[//rosettacode.org/wiki/Category:ZX_Spectrum_Basic ZX Spectrum page]]
--[[User:Frisian|Frisian]] ([[User talk:Frisian|talk]]) 17:44, 30 April 2020 (UTC)
Our 2nd reply:
actually 249^2*5^2, which is just under the internal limit of a Spectrum Next, & can be madesmaller by shifting indices down to 0
TO 248 and changing the code accordingly. Yet this beta does not have the same flaw as the alpha, as the m loop runs within the 4
others. The error should be different: in taking logs, subtracting them, exponentiating differences, and taking the log of their
sums, and comparing that to a log in the p array. That ought to compound rounding errors, so we wouldn't be surprised if it didn't
find the correct solution. Even so, we'd settle for it not finding false solutions. So we'll test it on a 2 MB QL on Q-emuLator
sometime next week, and also test trying to balance out the rounding errors on each side of the IF =sign. It seems that Sinclair
BASICs calculate an extra digit in FP functions so as to know which way to round the least significant digit. Comparing the 2.5
powers is to attempt a "meet inthe middle" hack to a discrete log problem. Thus, taking INTs becomes superfluous-& even when
comparing integers after taking INTs, which seems like shooting yourself in the foot: you may find the correct solution,
but you also may round some FP Nos the wrong way and thereby find false solutions.
The point is taken that a Spectrum Next is no ZX Spectrum, inwhich case one can revert back to no precalculated differences, and run that at full speed on Fuse.
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