From 0ac2c7c62b8fbd6df7deaed5bc9fe7e775dc997c Mon Sep 17 00:00:00 2001
From: Andreas Enge <andreas.enge@inria.fr>
Date: Tue, 4 Jul 2023 16:10:20 +0200
Subject: [PATCH] Increase Dmax to continue for a stuck number.
* lib/ecpp.c (ecpp1): Double the value of Dmax and add a maximum value.
---
lib/ecpp.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/lib/ecpp.c b/lib/ecpp.c
index f3e2c1d..08378e1 100644
--- a/lib/ecpp.c
+++ b/lib/ecpp.c
@@ -1309,12 +1309,16 @@ static mpz_t** ecpp1 (int *depth, mpz_srcptr p, char *filename,
more and more qstar, which becomes increasingly difficult. */
#endif
const uint_cl_t Dmax =
- 1ul << CM_MAX (20, (((unsigned long int) ceil (log2 (L*L))) - 2));
- /* We need a value that is a multiple of 4. To limit the number of
- possible values, we choose a power of 2 above the previously
- implemented L^2/4; the minimum of 2^20 leads to a negligible
- running time for the class numbers even on a single core. For a
- hypothetical number of 100000 digits, the value would be 2^35. */
+ 1ul << CM_MIN (35, CM_MAX (20,
+ ((unsigned long int) ceil (log2 (L*L)) - 1)));
+ /* We need a value that is a multiple of 4 and thus choose a power
+ of 2. The minimum of 2^20 leads to a negligible running time for
+ the class numbers even on a single core.
+ The value should grow like L^2.
+ Using L^2/4 led to a failure for a difficult number of 7028 digits,
+ L^2/2 let it pass with the discriminant -541*626887.
+ We use 2^35 as a maximum value, kicking in at about 79000 digits,
+ which leads to a class number file of 64 GB size. */
const uint_cl_t hmaxprime = CM_MAX (29, L>>10);
mpz_t N;
mpz_t** c;
--
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