From: Ben Lynn <benlynn@gmail.com>
Date: Wed, 17 Sep 2008 01:33:04 +0000 (-0700)
Subject: Newton's method for quadratics involving continued fractions.
X-Git-Url: https://repo.or.cz/w/frac.git/commitdiff_plain/b21535311747efaacb99d6b10ef2529ceee9d502

Newton's method for quadratics involving continued fractions.
---

diff --git a/Makefile b/Makefile
index bc49a6c..c61c560 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 .PHONY: test target clean
 
-CF_OBJS:=cf.o mobius.o famous.o bihom.o taylor.o test.o
-TESTS:=bihom_test cf_test famous_test mobius_test
+CF_OBJS:=cf.o mobius.o famous.o bihom.o taylor.o test.o newton.o
+TESTS:=bihom_test cf_test famous_test mobius_test newton_test
 BINS:=pi pi2 sqrt2 epow
 
 target : $(BINS)
diff --git a/cf.h b/cf.h
index c607946..f250a9c 100644
--- a/cf.h
+++ b/cf.h
@@ -72,4 +72,12 @@ cf_t cf_new_bihom(cf_t x, cf_t y, mpz_t a[8]);
 cf_t cf_new_sin1();
 cf_t cf_new_cos1();
 
+// From newton.c:
+// Use Newton's method to find solutions of:
+//
+//     a0 xy + a1 x + a2 y + a3
+// y = ------------------------
+//     a4 xy - a0 x + a5 y - a2
+cf_t cf_new_newton(cf_t x, mpz_t a[6]);
+
 #endif  // __CF_H__
diff --git a/cf_test.c b/cf_test.c
index c417a3e..e44229a 100644
--- a/cf_test.c
+++ b/cf_test.c
@@ -18,16 +18,31 @@ static void *count_fn(cf_t cf) {
   return NULL;
 }
 
+static void *count_int_fn(cf_t cf) {
+  int n = 0;
+  while(cf_wait(cf)) {
+    cf_put_int(cf, n);
+    n++;
+  }
+  return NULL;
+}
+
 int main() {
-  mpz_t z;
+  mpz_t z, z1;
   mpz_init(z);
-  cf_t a;
+  mpz_init(z1);
+  cf_t a, b;
   a = cf_new_const(count_fn);
+  b = cf_new_const(count_int_fn);
   for (int i = 0; i < 100; i++) {
     cf_get(z, a);
     EXPECT(!mpz_cmp_ui(z, i));
+    cf_get(z, b);
+    EXPECT(!mpz_cmp_ui(z, i));
   }
   cf_free(a);
+  cf_free(b);
   mpz_clear(z);
+  mpz_clear(z1);
   return 0;
 }
diff --git a/famous_test.c b/famous_test.c
index 10db391..7347660 100644
--- a/famous_test.c
+++ b/famous_test.c
@@ -9,10 +9,10 @@
 #include "test.h"
 
 int main() {
-  CF_NEW_EXPECT_DEC(cf_new_e, "2.718281828");
+  CF_NEW_EXPECT_DEC(cf_new_sqrt2, "1.41421356237309504880");
+  CF_NEW_EXPECT_DEC(cf_new_e, "2.71828182845904523536");
   CF_NEW_EXPECT_DEC(cf_new_pi, "3.1415926535897932384");
   CF_NEW_EXPECT_DEC(cf_new_tan1, "1.5574077246549022305");
-
   CF_NEW_EXPECT_DEC(cf_new_sin1, "0.8414709848078965066");
   CF_NEW_EXPECT_DEC(cf_new_cos1, "0.5403023058681397174");
   return 0;