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einstein1969
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- Joined: 15 Jun 2012 13:16
- Location: Italy, Rome
#46
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by einstein1969 » 25 May 2024 07:48
thanks.
I got to the point
"divide h.ighlow by 2 (updating the e_2 value) until 1 <= h.ighlow < 2".
Code: Select all
set "string= 8 4 2 "
for %%a in ("!high:~0,1!") do @for %%b in (!string:~-%%~a!) do @(
>nul set /A "c=(high&1)+1"
set "low=!c!!low!"
>nul set /A "high>>=1", "low=(low>>1)-50000000", "e_2+=1"
set "low=00000000!low!"
set "low=!low:~-8!"
)
Can you explain these two instructions to me, the first I don't understand why you do
set /A "c=(high&1)+1" and
I don't understand why in this
set /A "high>>=1", "low=(low >>1)-50000000", "e_2+=1" remove 50000000 from low/2.
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penpen
- Expert
- Posts: 2009
- Joined: 23 Jun 2013 06:15
- Location: Germany
#47
Post
by penpen » 25 May 2024 14:15
When i divide high by 2 (realized by high>>=1), then there is an underflow in case high contains an odd number.
I don't want to lose that underflowed portion, so i force it to be the leading character of low (low=!c!!low!).
But if the leading character of low is 0, then the set/a-command treats low as an octal number.
Therefore i have to make sure it's not zero, hence i added 1, resulting in "c=(high&1)+1".
To not change the value, I have to substract the value I've added (or half of the value, once i divided by 2) and
I also have to increase the exponent to the basis of two by one, resulting in ""high>>=1", "low=(low>>1)-50000000", "e_2+=1"".
The last two lines ensure that low contains exactly 8 digits.
penpen
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einstein1969
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- Posts: 957
- Joined: 15 Jun 2012 13:16
- Location: Italy, Rome
#48
Post
by einstein1969 » 27 May 2024 17:22
ok, I was going crazy to figure out that +1.
These days I've had to slow down because my only PC is having problems and isn't working well.