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authormrkn <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2011-06-17 17:38:14 +0000
committermrkn <mrkn@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2011-06-17 17:38:14 +0000
commitf107d1e7066fdfa6360bf4aa9986f519dcd3f175 (patch)
treefff0efb2089cbee7737ff7407b8e8baa5cc196bf /ext/bigdecimal/bigdecimal.c
parenta489109884de316893e3e716130be3a48bb965f0 (diff)
* ext/bigdecimal/bigdecimal.c (BigMath_s_exp): move BigMath.exp from
bigdecimal/math.rb. * ext/bigdecimal/lib/bigdecimal/math.rb: ditto. * test/bigdecimal/test_bigdecimal.rb: move test for BigMath.exp from test/bigdecimal/test_bigmath.rb. * test/bigdecimal/test_bigmath.rb: ditto. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32150 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'ext/bigdecimal/bigdecimal.c')
-rw-r--r--ext/bigdecimal/bigdecimal.c136
1 files changed, 136 insertions, 0 deletions
diff --git a/ext/bigdecimal/bigdecimal.c b/ext/bigdecimal/bigdecimal.c
index 3badb03..4fc22b5 100644
--- a/ext/bigdecimal/bigdecimal.c
+++ b/ext/bigdecimal/bigdecimal.c
@@ -34,6 +34,7 @@
/* #define ENABLE_NUMERIC_STRING */
VALUE rb_cBigDecimal;
+VALUE rb_mBigMath;
static ID id_BigDecimal_exception_mode;
static ID id_BigDecimal_rounding_mode;
@@ -2000,6 +2001,137 @@ BigDecimal_save_limit(VALUE self)
return ret;
}
+/* call-seq:
+ * BigMath.exp(x, prec)
+ *
+ * Computes the value of e (the base of natural logarithms) raised to the
+ * power of x, to the specified number of digits of precision.
+ *
+ * If x is infinite, returns Infinity.
+ *
+ * If x is NaN, returns NaN.
+ */
+static VALUE
+BigMath_s_exp(VALUE klass, VALUE x, VALUE vprec)
+{
+ ssize_t prec, n, i;
+ Real* vx = NULL;
+ VALUE one, d, x1, y, z;
+ int negative = 0;
+ int infinite = 0;
+ int nan = 0;
+ double flo;
+
+ prec = NUM2SSIZET(vprec);
+ if (prec <= 0) {
+ rb_raise(rb_eArgError, "Zero or negative precision for exp");
+ }
+
+ /* TODO: the following switch statement is almostly the same as one in the
+ * BigDecimalCmp function. */
+ switch (TYPE(x)) {
+ case T_DATA:
+ if (!is_kind_of_BigDecimal(x)) break;
+ vx = DATA_PTR(x);
+ negative = VpGetSign(vx) < 0;
+ infinite = VpIsPosInf(vx) || VpIsNegInf(vx);
+ nan = VpIsNaN(vx);
+ break;
+
+ case T_FIXNUM:
+ /* fall through */
+ case T_BIGNUM:
+ vx = GetVpValue(x, 0);
+ break;
+
+ case T_FLOAT:
+ flo = RFLOAT_VALUE(x);
+ negative = flo < 0;
+ infinite = isinf(flo);
+ nan = isnan(flo);
+ if (!infinite && !nan) {
+ vx = GetVpValueWithPrec(x, DBL_DIG+1, 0);
+ }
+ break;
+
+ case T_RATIONAL:
+ vx = GetVpValueWithPrec(x, prec, 0);
+ break;
+
+ default:
+ break;
+ }
+ if (infinite) {
+ if (negative) {
+ return ToValue(GetVpValueWithPrec(INT2NUM(0), prec, 1));
+ }
+ else {
+ Real* vy;
+ vy = VpCreateRbObject(prec, "#0");
+ RB_GC_GUARD(vy->obj);
+ VpSetInf(vy, VP_SIGN_POSITIVE_INFINITE);
+ return ToValue(vy);
+ }
+ }
+ else if (nan) {
+ Real* vy;
+ vy = VpCreateRbObject(prec, "#0");
+ RB_GC_GUARD(vy->obj);
+ VpSetNaN(vy);
+ return ToValue(vy);
+ }
+ else if (vx == NULL) {
+ rb_raise(rb_eArgError, "%s can't be coerced into BigDecimal",
+ rb_special_const_p(x) ? RSTRING_PTR(rb_inspect(x)) : rb_obj_classname(x));
+ }
+ RB_GC_GUARD(vx->obj);
+
+ n = prec + rmpd_double_figures();
+ negative = VpGetSign(vx) < 0;
+ if (negative) {
+ VpSetSign(vx, 1);
+ }
+
+ RB_GC_GUARD(one) = ToValue(VpCreateRbObject(1, "1"));
+ RB_GC_GUARD(x1) = one;
+ RB_GC_GUARD(y) = one;
+ RB_GC_GUARD(d) = y;
+ RB_GC_GUARD(z) = one;
+ i = 0;
+
+ while (!VpIsZero((Real*)DATA_PTR(d))) {
+ VALUE argv[2];
+ SIGNED_VALUE const ey = VpExponent10(DATA_PTR(y));
+ SIGNED_VALUE const ed = VpExponent10(DATA_PTR(d));
+ ssize_t m = n - vabs(ey - ed);
+ if (m <= 0) {
+ break;
+ }
+ else if ((size_t)m < rmpd_double_figures()) {
+ m = rmpd_double_figures();
+ }
+
+ x1 = BigDecimal_mult2(x1, x, SSIZET2NUM(n));
+ ++i;
+ z = BigDecimal_mult(z, SSIZET2NUM(i));
+ argv[0] = z;
+ argv[1] = SSIZET2NUM(m);
+ d = BigDecimal_div2(2, argv, x1);
+ y = BigDecimal_add(y, d);
+ }
+
+ if (negative) {
+ VALUE argv[2];
+ argv[0] = y;
+ argv[1] = vprec;
+ return BigDecimal_div2(2, argv, one);
+ }
+ else {
+ vprec = SSIZET2NUM(prec - VpExponent10(DATA_PTR(y)));
+ return BigDecimal_round(1, &vprec, y);
+ }
+}
+
/* Document-class: BigDecimal
* BigDecimal provides arbitrary-precision floating point decimal arithmetic.
*
@@ -2295,6 +2427,10 @@ Init_bigdecimal(void)
rb_define_method(rb_cBigDecimal, "truncate", BigDecimal_truncate, -1);
rb_define_method(rb_cBigDecimal, "_dump", BigDecimal_dump, -1);
+ /* mathematical functions */
+ rb_mBigMath = rb_define_module("BigMath");
+ rb_define_singleton_method(rb_mBigMath, "exp", BigMath_s_exp, 2);
+
id_BigDecimal_exception_mode = rb_intern_const("BigDecimal.exception_mode");
id_BigDecimal_rounding_mode = rb_intern_const("BigDecimal.rounding_mode");
id_BigDecimal_precision_limit = rb_intern_const("BigDecimal.precision_limit");