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comparison liboctave/Range.cc @ 3858:de05e6bdf897

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[project @ 2001-11-08 19:34:22 by jwe]
author jwe
date Thu, 08 Nov 2001 19:34:23 +0000
parents f751e43de300
children 6e86256e9c54
comparison
equal deleted inserted replaced
3857:f7c7ecb63a7e 3858:de05e6bdf897
240 } 240 }
241 241
242 int 242 int
243 Range::nelem_internal (void) const 243 Range::nelem_internal (void) const
244 { 244 {
245 double ct = 3.0 * DBL_EPSILON; 245 int retval = -1;
246 246
247 double tmp = tfloor ((rng_limit - rng_base + rng_inc) / rng_inc, ct); 247 if (rng_inc == 0
248 248 || (rng_limit > rng_base && rng_inc < 0)
249 int n_elt = (tmp > 0.0 ? static_cast<int> (tmp) : 0); 249 || (rng_limit < rng_base && rng_inc > 0))
250 250 {
251 // If the final element that we would compute for the range is equal 251 retval = 0;
252 // to the limit of the range, or is an adjacent floating point 252 }
253 // number, accept it. Otherwise, try a range with one fewer 253 else
254 // element. If that fails, try again with one more element. 254 {
255 // 255 double ct = 3.0 * DBL_EPSILON;
256 // I'm not sure this is very good, but it seems to work better than 256
257 // just using tfloor as above. For example, without it, the 257 double tmp = tfloor ((rng_limit - rng_base + rng_inc) / rng_inc, ct);
258 // expression 1.8:0.05:1.9 fails to produce the expected result of 258
259 // [1.8, 1.85, 1.9]. 259 int n_elt = (tmp > 0.0 ? static_cast<int> (tmp) : 0);
260 260
261 if (! teq (rng_base + (n_elt - 1) * rng_inc, rng_limit)) 261 // If the final element that we would compute for the range is
262 { 262 // equal to the limit of the range, or is an adjacent floating
263 if (teq (rng_base + (n_elt - 2) * rng_inc, rng_limit)) 263 // point number, accept it. Otherwise, try a range with one
264 n_elt--; 264 // fewer element. If that fails, try again with one more
265 else if (teq (rng_base + n_elt * rng_inc, rng_limit)) 265 // element.
266 n_elt++; 266 //
267 } 267 // I'm not sure this is very good, but it seems to work better than
268 268 // just using tfloor as above. For example, without it, the
269 return (n_elt >= INT_MAX - 1) ? -1 : n_elt; 269 // expression 1.8:0.05:1.9 fails to produce the expected result of
270 // [1.8, 1.85, 1.9].
271
272 if (! teq (rng_base + (n_elt - 1) * rng_inc, rng_limit))
273 {
274 if (teq (rng_base + (n_elt - 2) * rng_inc, rng_limit))
275 n_elt--;
276 else if (teq (rng_base + n_elt * rng_inc, rng_limit))
277 n_elt++;
278 }
279
280 retval = (n_elt >= INT_MAX - 1) ? -1 : n_elt;
281 }
282
283 return retval;
270 } 284 }
271 285
272 /* 286 /*
273 ;;; Local Variables: *** 287 ;;; Local Variables: ***
274 ;;; mode: C++ *** 288 ;;; mode: C++ ***