caching mechanism in solveLinearPolynomialEquation

[Qian Yun]

In function 'solveLinearPolynomialEquation' in integer.spad,
gaussian.spad and ffcat.spad, the code appears to have a
caching mechanism via 'oldlp' and 'oldtable', but the cache
will never work because 'oldlp' is never updated with the
last value.

Shall we fix the caching mechanism or remove it?

- Qian

--- a/src/algebra/integer.spad
+++ b/src/algebra/integer.spad
@@ -39,6 +39,7 @@
if (ans case "failed") then
slpePrime :=
prevPrime(slpePrime)$IntegerPrimesPackage(Integer)
oldtable := (ans:: Vector List ZP)
+ oldlp := lp
answer := solveid(p, slpePrime, oldtable)
answer

[Waldek Hebisch]

On Sat, Jul 11, 2026 at 05:09:58PM +0800, Qian Yun wrote:
> In function 'solveLinearPolynomialEquation' in integer.spad,
> gaussian.spad and ffcat.spad, the code appears to have a
> caching mechanism via 'oldlp' and 'oldtable', but the cache
> will never work because 'oldlp' is never updated with the
> last value.
>
> Shall we fix the caching mechanism or remove it?

As for now fix. I work on replacemt factorizer which hopefully
will be ready to replace current one after next release, so
in say a year this code should be no longer needed. But for
now caching should give some speedup.

> --- a/src/algebra/integer.spad
> +++ b/src/algebra/integer.spad
> @@ -39,6 +39,7 @@
> if (ans case "failed") then
> slpePrime :=
> prevPrime(slpePrime)$IntegerPrimesPackage(Integer)
> oldtable := (ans:: Vector List ZP)
> + oldlp := lp
> answer := solveid(p, slpePrime, oldtable)
> answer
>
>

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--
Waldek Hebisch