[libmath-prime-util-perl] 62/181: Add moebius/exp_mangoldt to util.c

[Partha P. Mukherjee]

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ppm-guest pushed a commit to annotated tag v0.36
in repository libmath-prime-util-perl.

commit 2696cc6ed4931d76ef1f310838df796859a82613
Author: Dana Jacobsen <dana at acm.org>
Date:   Mon Dec 30 01:15:42 2013 -0800

    Add moebius/exp_mangoldt to util.c
---
 Changes |  6 ++++--
 util.c  | 32 ++++++++++++++++++++++++++++++++
 util.h  |  2 ++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/Changes b/Changes
index 2eff5b0..3358497 100644
--- a/Changes
+++ b/Changes
@@ -21,6 +21,10 @@ Revision history for Perl module Math::Prime::Util
 
     [FUNCTIONALITY AND PERFORMANCE]
 
+    - Win32 fixes from bulk88 / bulkdd.  Thanks!
+
+    - Lots of XS interface reorgs.
+
     - Speedup for input number validation: speedup for all functions,
       especially noticeable with fast functions (e.g. small n is_prime(n)).
 
@@ -43,8 +47,6 @@ Revision history for Perl module Math::Prime::Util
 
     - znorder uses Carmichael Lambda instead of Euler Phi.  Faster.
 
-    - carmichael_lambda switched to XS->Perl from Perl->XS.
-
 
 0.35  2013-12-08
 
diff --git a/util.c b/util.c
index 336a333..855b592 100644
--- a/util.c
+++ b/util.c
@@ -825,6 +825,7 @@ UV* _totient_range(UV lo, UV hi) {
   UV* totients;
   UV i;
   if (hi < lo) croak("_totient_range error hi %lu < lo %lu\n", hi, lo);
+  /* TODO: When is it faster to just do individual calls? */
   New(0, totients, hi-lo+1, UV);
   if (totients == 0)
     croak("Could not get memory for %"UVuf" totients\n", hi);
@@ -980,6 +981,37 @@ UV carmichael_lambda(UV n) {
   return lambda;
 }
 
+int moebius(UV n) {
+  UV factors[MPU_MAX_FACTORS+1];
+  UV i, nfactors;
+  if (n <= 1) return (int)n;
+
+  if ( (!(n% 4) && n >=  4) || (!(n% 9) && n >=  9) ||
+       (!(n%25) && n >= 25) || (!(n%49) && n >= 49) )
+    return 0;
+
+  nfactors = factor(n, factors);
+  for (i = 1; i < nfactors; i++)
+    if (factors[i] == factors[i-1])
+      return 0;
+  return (nfactors % 2) ? -1 : 1;
+}
+
+UV exp_mangoldt(UV n) {
+  if      (n <= 1)           return 1;
+  else if ((n & (n-1)) == 0) return 2;     /* Power of 2 */
+  else if ((n & 1) == 0)     return 1;     /* Even number (not 2) */
+  else {
+    UV i, factors[MPU_MAX_FACTORS+1];
+    UV nfactors = factor(n, factors);
+    for (i = 1; i < nfactors; i++) 
+      if (factors[i] != factors[0])
+        return 1;
+    return factors[0];
+  }
+}
+
+
 UV znorder(UV a, UV n) {
   UV fac[MPU_MAX_FACTORS+1];
   UV exp[MPU_MAX_FACTORS+1];
diff --git a/util.h b/util.h
index 1cb51d5..6cb0cbb 100644
--- a/util.h
+++ b/util.h
@@ -32,6 +32,8 @@ extern int kronecker_su(IV a, UV b);
 extern int kronecker_ss(IV a, IV b);
 
 extern UV totient(UV n);
+extern int moebius(UV n);
+extern UV exp_mangoldt(UV n);
 extern UV carmichael_lambda(UV n);
 extern UV znprimroot(UV n);
 extern UV znorder(UV a, UV n);

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