Changeset eb5966 in git for ntl/src/xdouble.c

Timestamp:

Sep 14, 2004, 2:00:40 PM (20 years ago)

Author:

Hans Schönemann <hannes@…>

Branches:

(u'fieker-DuVal', '117eb8c30fc9e991c4decca4832b1d19036c4c65')(u'spielwiese', 'b9f50b373314e74e83c7c060a651dd2913e1f033')

Children:

3119025bf9047f84e9ab4e733bd2fdef4b6c422e

Parents:

e6caf814a009946e5e934ceda7f851b656e36e41

Message:

*hannes: 5.3.2


git-svn-id: file:///usr/local/Singular/svn/trunk@7473 2c84dea3-7e68-4137-9b89-c4e89433aadc

File:

• ntl/src/xdouble.c (modified) (1 diff)

ntl/src/xdouble.c

@@ -610 +610 @@
 
    return x3;
+}
+
+
+
+
+ostream& operator<<(ostream& s, const xdouble& a)
+{
+   if (a == 0) {
+      s << "0";
+      return s;
+   }
+
+   long old_p = RR::precision();
+   long temp_p = long(log(fabs(log(fabs(a))) + 1.0)/log(2.0)) + 10; 
+
+   RR::SetPrecision(temp_p);
+
+   RR ln2, ln10, log_2_10;
+   ComputeLn2(ln2);
+   ComputeLn10(ln10);
+   log_2_10 = ln10/ln2;
+   ZZ log_10_a = to_ZZ(
+  (to_RR(a.e)*to_RR(2*NTL_XD_HBOUND_LOG) + log(fabs(a.x))/log(2.0))/log_2_10);
+
+   RR::SetPrecision(old_p);
+
+   xdouble b;
+   long neg;
+
+   if (a < 0) {
+      b = -a;
+      neg = 1;
+   }
+   else {
+      b = a;
+      neg = 0;
+   }
+
+   ZZ k = xdouble::OutputPrecision() - log_10_a;
+
+   xdouble c, d;
+
+   c = PowerOf10(to_ZZ(xdouble::OutputPrecision()));
+   d = PowerOf10(log_10_a);
+
+   b = b / d;
+   b = b * c;
+
+   while (b < c) {
+      b = b * 10.0;
+      k++;
+   }
+
+   while (b >= c) {
+      b = b / 10.0;
+      k--;
+   }
+
+   b = b + 0.5;
+   k = -k;
+
+   ZZ B;
+   conv(B, b);
+
+   long bp_len = xdouble::OutputPrecision()+10;
+
+   char *bp = NTL_NEW_OP char[bp_len];
+
+   if (!bp) Error("xdouble output: out of memory");
+
+   long len, i;
+
+   len = 0;
+   do {
+      if (len >= bp_len) Error("xdouble output: buffer overflow");
+      bp[len] = IntValToChar(DivRem(B, B, 10));
+      len++;
+   } while (B > 0);
+
+   for (i = 0; i < len/2; i++) {
+      char tmp;
+      tmp = bp[i];
+      bp[i] = bp[len-1-i];
+      bp[len-1-i] = tmp;
+   }
+
+   i = len-1;
+   while (bp[i] == '0') i--;
+
+   k += (len-1-i);
+   len = i+1;
+
+   bp[len] = '\0';
+
+   if (k > 3 || k < -len - 3) {
+      // use scientific notation
+
+      if (neg) s << "-";
+      s << "0." << bp << "e" << (k + len);
+   }
+   else {
+      long kk = to_long(k);
+
+      if (kk >= 0) {
+         if (neg) s << "-";
+         s << bp;
+         for (i = 0; i < kk; i++) 
+            s << "0";
+      }
+      else if (kk <= -len) {
+         if (neg) s << "-";
+         s << "0.";
+         for (i = 0; i < -len-kk; i++)
+            s << "0";
+         s << bp;
+      }
+      else {
+         if (neg) s << "-";
+         for (i = 0; i < len+kk; i++)
+            s << bp[i];
+   
+         s << ".";
+   
+         for (i = len+kk; i < len; i++)
+            s << bp[i];
+      }
+   }
+
+   delete [] bp;
+   return s;
+}
+
+istream& operator>>(istream& s, xdouble& x)
+{
+   long c;
+   long cval;
+   long sign;
+   ZZ a, b;
+
+   if (!s) Error("bad xdouble input");
+
+   c = s.peek();
+   while (IsWhiteSpace(c)) {
+      s.get();
+      c = s.peek();
+   }
+
+   if (c == '-') {
+      sign = -1;
+      s.get();
+      c = s.peek();
+   }
+   else
+      sign = 1;
+
+   long got1 = 0;
+   long got_dot = 0;
+   long got2 = 0;
+
+   a = 0;
+   b = 1;
+
+   cval = CharToIntVal(c);
+
+   if (cval >= 0 && cval <= 9) {
+      got1 = 1;
+
+      while (cval >= 0 && cval <= 9) {
+         mul(a, a, 10);
+         add(a, a, cval);
+         s.get();
+         c = s.peek();
+         cval = CharToIntVal(c);
+      }
+   }
+
+   if (c == '.') {
+      got_dot = 1;
+
+      s.get();
+      c = s.peek();
+      cval = CharToIntVal(c);
+
+      if (cval >= 0 && cval <= 9) {
+         got2 = 1;
+   
+         while (cval >= 0 && cval <= 9) {
+            mul(a, a, 10);
+            add(a, a, cval);
+            mul(b, b, 10);
+            s.get();
+            c = s.peek();
+            cval = CharToIntVal(c);
+         }
+      }
+   }
+
+   if (got_dot && !got1 && !got2)  Error("bad xdouble input");
+
+   ZZ e;
+
+   long got_e = 0;
+   long e_sign;
+
+   if (c == 'e' || c == 'E') {
+      got_e = 1;
+
+      s.get();
+      c = s.peek();
+
+      if (c == '-') {
+         e_sign = -1;
+         s.get();
+         c = s.peek();
+      }
+      else if (c == '+') {
+         e_sign = 1;
+         s.get();
+         c = s.peek();
+      }
+      else
+         e_sign = 1;
+
+      cval = CharToIntVal(c);
+
+      if (cval < 0 || cval > 9) Error("bad xdouble input");
+
+      e = 0;
+      while (cval >= 0 && cval <= 9) {
+         mul(e, e, 10);
+         add(e, e, cval);
+         s.get();
+         c = s.peek();
+         cval = CharToIntVal(c);
+      }
+   }
+
+   if (!got1 && !got2 && !got_e) Error("bad xdouble input");
+
+   xdouble t1, t2, v;
+
+   if (got1 || got2) {
+      conv(t1, a);
+      conv(t2, b);
+      v = t1/t2;
+   }
+   else
+      v = 1;
+
+   if (sign < 0)
+      v = -v;
+
+   if (got_e) {
+      if (e_sign < 0) negate(e, e);
+      t1 = PowerOf10(e);
+      v = v * t1;
+   }
+
+   x = v;
+   return s;
 }