klisp

commit 51b19792042a7cc65292698f0a4c947f426ffcc6
parent 4ef1dabaea247b73f87767e529e87b5bb865b5b7
Author: Andres Navarro <canavarro82@gmail.com>
Date:   Sun,  1 May 2011 01:23:21 -0300

Added rational->real conversion.

Diffstat:
M
src/kreal.c
 | 
59
+++++++++++++++++++++++++++++++++++++++++++++++++++++++----

1 file changed, 55 insertions(+), 4 deletions(-)
diff --git a/src/kreal.c b/src/kreal.c
@@ -28,8 +28,6 @@
 	else res = d2tv(d__);						\
 	res;})
 
-
-
 double kbigint_to_double(Bigint *bigint)
 {
     double radix = (double) UINT32_MAX + 1.0;
@@ -45,6 +43,58 @@ double kbigint_to_double(Bigint *bigint)
     return mp_int_compare_zero(bigint) < 0? -accum : accum;
 }
 
+/* bigrat is rooted */
+double kbigrat_to_double(klisp_State *K, Bigrat *bigrat)
+{	
+    TValue tv_rem = kbigrat_copy(K, gc2bigrat(bigrat));
+    krooted_tvs_push(K, tv_rem);
+    Bigrat *rem = tv2bigrat(tv_rem);
+    UNUSED(mp_rat_abs(K, rem, rem)); 
+
+    TValue int_radix = kbigint_make_simple(K);
+    krooted_tvs_push(K, int_radix);
+    /* cant do UINT32_MAX and then +1 because _value functions take 
+       int32_t arguments */ 
+    UNUSED(mp_int_set_value(K, tv2bigint(int_radix), INT32_MAX)); 
+    UNUSED(mp_int_add_value(K, tv2bigint(int_radix), 1, 
+			    tv2bigint(int_radix)));
+    UNUSED(mp_int_add(K, tv2bigint(int_radix), tv2bigint(int_radix), 
+		      tv2bigint(int_radix)));
+
+    TValue int_part = kbigint_make_simple(K);
+    krooted_tvs_push(K, int_part);
+
+    double accum = 0.0;
+    double radix = (double) UINT32_MAX + 1.0;
+    uint32_t digit = 0;
+    /* inside there is a check to avoid problem with continuing fractions */
+    while(mp_rat_compare_zero(rem) > 0) {
+	UNUSED(mp_int_div(K, MP_NUMER_P(rem), MP_DENOM_P(rem), 
+			  tv2bigint(int_part), NULL));
+
+	double di = kbigint_to_double(tv2bigint(int_part));
+	bool was_zero = di == 0.0;
+	for (uint32_t i = 0; i < digit; i++) {
+	    di /= radix;
+	}
+	/* if last di became 0.0 we will exit next loop,
+	   this is to avoid problem with continuing fractions */
+	if (!was_zero && di == 0.0)
+	    break;
+
+	++digit;
+	accum += di; 
+	
+	UNUSED(mp_rat_sub_int(K, rem, tv2bigint(int_part), rem));
+	UNUSED(mp_rat_mul_int(K, rem, tv2bigint(int_radix), rem));
+    }
+    krooted_tvs_pop(K); /* int_part */
+    krooted_tvs_pop(K); /* int_radix */
+    krooted_tvs_pop(K); /* rem */
+
+    return mp_rat_compare_zero(bigrat) < 0? -accum : accum;
+}
+
 TValue kexact_to_inexact(klisp_State *K, TValue n)
 {
     switch(ttype(n)) {
@@ -58,8 +108,9 @@ TValue kexact_to_inexact(klisp_State *K, TValue n)
 	return ktag_double(d);
     }
     case K_TBIGRAT: {
-	klisp_assert(0);
-	return KUNDEF;
+	Bigrat *bigrat = tv2bigrat(n);
+	double d = kbigrat_to_double(K, bigrat);
+	return ktag_double(d);
     }
     case K_TEINF:
 	return tv_equal(n, KEPINF)? KIPINF : KIMINF;