Re: 2^[1,3]

On 2025-01-29 14:42, Bill Allombert wrote:
 > On Wed, Jan 29, 2025 at 02:28:46PM +0100, Ruud H.G. van Tol wrote:

 >> ? vecsum(2^[1,3])
 >> % 10.000000000000000000000000000000000000
 >
 > Use fromdigits:
 > ? fromdigits([1,3],2)
 > % = 10

Doesn't work:

? fromdigits([1,3],2)
% = 5
(because 1*2^1 + 3*2^0 = 2+3 = 5)


The (distinct) digits are exponents, are not positional.
2^1 + 2^3 = 10.


Example quest:

 >> How to best convert something like (int) 6131786 to (int) 2^1 + 2^3 
+ 2^6 +
 >> 2^7 + 2^8?
 >
 > You can use the binary() function.

I don't see yet how.

-- Ruud