User talk:Retroburrowers: Difference between revisions
Content added Content deleted
m (errors omitted) |
m (clarity added) |
||
Line 92: | Line 92: | ||
Please check [[//rosettacode.org/wiki/Category:ZX_Spectrum_Basic ZX Spectrum page]] |
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) |
--[[User:Frisian|Frisian]] ([[User talk:Frisian|talk]]) 17:44, 30 April 2020 (UTC) |
||
Our 2nd reply: |
Our 2nd reply: |
||
actually 249^2*5 is within the |
actually 249^2*5 is within the OEM limit of a QL, & can be made smaller 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 |
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 |
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 Q-emuLator |
find the correct solution. Even so, we'd settle for it not finding false solutions. So we'll test it 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 |
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 - just as |
powers is to attempt a "meet inthe middle" hack to a discrete log problem. Thus, taking INTs becomes superfluous - just as like |
||
comparing integers by taking INTs, which seems like shooting yourself in the foot: you may find the correct solution, |
when comparing integers by 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. |
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, |
The point is taken that a Spectrum Next is no ZX Spectrum, in which case one can revert back to no precalculated differences, and run that at full speed on Fuse. |