[genius] Wed Dec 07 01:40:42 2011 Jiri (George) Lebl <jirka 5z com>

[George Lebl <jirka src gnome org>]

commit f88fb97c691e63613052925e6ac98b724dae0627
Author: Jiri (George) Lebl <jirka 5z com>
Date:   Wed Dec 7 01:40:51 2011 -0600

    Wed Dec 07 01:40:42 2011  Jiri (George) Lebl <jirka 5z com>
    
    	* src/mpwrap.c: fix roots of negative numbers when numerator of power
    	  is positive.  Also fix exact roots when power is negative.
    
    	* src/geniustests.txt: add tests for above

 ChangeLog           |    7 ++++++
 src/geniustests.txt |    9 ++++++++
 src/mpwrap.c        |   55 +++++++++++++++++++++++++++++++++++++++-----------
 3 files changed, 59 insertions(+), 12 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 9748a71..5b91133 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Wed Dec 07 01:40:42 2011  Jiri (George) Lebl <jirka 5z com>
+
+	* src/mpwrap.c: fix roots of negative numbers when numerator of power
+	  is positive.  Also fix exact roots when power is negative.
+
+	* src/geniustests.txt: add tests for above
+
 Fri Nov 18 00:53:09 2011  Jiri (George) Lebl <jirka 5z com>
 
 	* src/symbolic.c: accept log instead of ln for natural log when doing
diff --git a/src/geniustests.txt b/src/geniustests.txt
index ff26a38..65698e8 100644
--- a/src/geniustests.txt
+++ b/src/geniustests.txt
@@ -1081,6 +1081,15 @@ j=0;(for n=1 to 20 do (for d=1 to 20 do (if n!=(sum r in ColumnsOf(MacaulayRep(n
 MacaulayRep(27,3)						[6,4,1;3,2,1]
 MacaulayBound(27,3)						46
 MacaulayLowerOperator(27,3)					13
+(-8)^(1/3)							-2
+(-1/8)^(1/3)							-1/2
+(-2)^(1/3)							-1.25992104989
+(-8)^(-1/3)							-1/2
+(-1/8)^(-1/3)							-2
+(-2)^(-1/3)							-0.793700525984
+(-8)^(-2/3)							1/4
+(-1/8)^(-2/3)							4
+(-2)^(-2/3)							0.629960524947
 load "nullspacetest.gel"					true
 load "longtest.gel"						true
 load "testprec.gel"						true
diff --git a/src/mpwrap.c b/src/mpwrap.c
index 72758ac..363aa70 100644
--- a/src/mpwrap.c
+++ b/src/mpwrap.c
@@ -1815,12 +1815,25 @@ mpwl_pow_q(MpwRealNum *rop,MpwRealNum *op1,MpwRealNum *op2)
 			GET_INIT_MPZ (z);
 
 			if (mpz_root (z, op1->data.ival, den) != 0) {
-				mympz_pow_z (z, z,
-					     mpq_numref (op2->data.rval));
-				mpwl_clear (rop);
-				rop->type = MPW_INTEGER;
-				memcpy (rop->data.ival, z,
-					sizeof (__mpz_struct));
+				mpz_ptr num = mpq_numref (op2->data.rval);
+				if (mpz_sgn (num) < 0) {
+					mpz_neg (num, num);
+					mympz_pow_z (z, z, num);
+					mpz_neg (num, num);
+					mpwl_clear (rop);
+					rop->type = MPW_RATIONAL;
+					mpq_init (rop->data.rval);
+					mpq_set_z (rop->data.rval, z);
+					mpq_inv (rop->data.rval,
+						 rop->data.rval);
+					CLEAR_FREE_MPZ (z);
+				} else {
+					mympz_pow_z (z, z, num);
+					mpwl_clear (rop);
+					rop->type = MPW_INTEGER;
+					memcpy (rop->data.ival, z,
+						sizeof (__mpz_struct));
+				}
 
 				return FALSE;
 			}
@@ -1835,15 +1848,31 @@ mpwl_pow_q(MpwRealNum *rop,MpwRealNum *op1,MpwRealNum *op2)
 			    mpz_root (mpq_denref (q),
 				      mpq_denref (op1->data.rval),
 				      den) != 0) {
-				mympz_pow_z (mpq_numref (q), mpq_numref (q),
-					     mpq_numref (op2->data.rval));
-				mympz_pow_z (mpq_denref (q), mpq_denref (q),
-					     mpq_numref (op2->data.rval));
+				mpz_ptr num = mpq_numref (op2->data.rval);
+				if (mpz_sgn (num) < 0) {
+					mpz_neg (num, num);
+					mympz_pow_z (mpq_numref (q),
+						     mpq_numref (q),
+						     num);
+					mympz_pow_z (mpq_denref (q),
+						     mpq_denref (q),
+						     num);
+					mpz_neg (num, num);
+					mpq_inv (q, q);
+				} else {
+					mympz_pow_z (mpq_numref (q),
+						     mpq_numref (q),
+						     num);
+					mympz_pow_z (mpq_denref (q),
+						     mpq_denref (q),
+						     num);
+				}
 				mpwl_clear (rop);
 				rop->type = MPW_RATIONAL;
 				memcpy (rop->data.rval, q,
 					sizeof (__mpq_struct));
-				mpq_canonicalize (rop->data.rval);
+				// the below does mpq_canonicalize
+				mpwl_make_int (rop);
 
 				return FALSE;
 			}
@@ -1864,7 +1893,9 @@ mpwl_pow_q(MpwRealNum *rop,MpwRealNum *op1,MpwRealNum *op2)
 		mpfr_neg (op1_f, op1_f, GMP_RNDN);
 		mpfr_pow (r.data.fval, op1_f, op2_f, GMP_RNDN);
 		mpfr_neg (op1_f, op1_f, GMP_RNDN);
-		mpfr_neg (r.data.fval, r.data.fval, GMP_RNDN);
+		if (mpz_odd_p (mpq_numref(op2->data.rval))) {
+			mpfr_neg (r.data.fval, r.data.fval, GMP_RNDN);
+		}
 	} else {
 		mpfr_pow (r.data.fval, op1_f, op2_f, GMP_RNDN);
 	}