Look at
https://fricas.github.io/api/PAdicRational.html
PAdicRational is build on InnerPAdicInteger. And that in turn is
implemented as Stream(Integer).
https://github.com/fricas/fricas/blob/master/src/algebra/padic.spad#L77
So, in generaal, FriCAS has to save and read a stream. While this is not
completely impossible (because a stream is also in memory just described
with a finite amount of data), the way it is done via your write!(f,A)
cannot work, since that does obviously only write out the first few
values of the stream. In fact, "NullStream" is a special way to denote
"the end of the stream". Unfortunately, FriCAS doesn't seem to handle
this case well when reading your file.
Since some streams are finite, the situation could be cured for them,
but what would it help? Potentially, streams are infinity and to do it
properly, the file should contain exactly the data that produces the
stream, i.e., the first few values together with a PROGRAM that computes
any following value.
Does that explain the problem?
Ralf
On 15.04.23 17:18, Sid Andal wrote:
A matrix of type PAdicRational is defined and saved in a file. However,
attempting to read it back leads to an error:
PR ==> PAdicRational(13)
SQ ==> SQMATRIX(4, PR)
A : SQ := [[2, 3, 5, 0], [7, 11, 12, 4], [3, 8, 6, 10], [12, 9, 8, 5]]
typeOf A
SquareMatrix(4,PAdicRational(13))
f : File SQ := open("PaMat4x4.out", "output")
write!(f,A)
close!(f)
$ cat PaMat4x4.out
#2A(((0 2 #1="NullStream") (0 3 #1#) (0 5 #1#) (0 #1#))
((0 7 #1#) (0 11 #1#) (0 12 #1#) (0 4 #1#))
((0 3 #1#) (0 8 #1#) (0 6 #1#) (0 10 #1#))
((0 12 #1#) (0 9 #1#) (0 8 #1#) (0 5 #1#)))
$ cp PaMat4x4.out PaMat4x4.input
fn := filename("", "PaMat4x4", "input")$FileName
f := open(fn, "input")$File(SQ)
B : SQ := read!(f)
System error:
The value "NullStream" is not of type INTEGER.
Removing the string "NullStream" doesn't seem to help....it leads to
other types of errors.
Thanks,
SWA
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