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>>>>> "Ed" == Ed Hartnett <ed@xxxxxxxxxxxxxxxx> writes:
Ed> float float_data_out2[DIM1_LEN] = {(float)INT_MIN - 1.0, (float)INT_MIN
- 1.0, (float)INT_MAX + 129.0};
Hi Ed,
Looking at your output, you're on a machine where
sizeof(float)==sizeof(int)==4. So the initialization of
float_data_out2[] is not doing what you expect. The problem is that
the significand of a float is less than 32 bits (because the sign and
exponent take up some of the other bits). So the +1.0 and -1.0 have
too small a magnitude to make any difference in the arithmetic. The
loss of significant digits can be seen in your output: INT_MIN-1.0
should be -2147483649, not -2147483648.
Ed> So why doesn't it generate an overflow?
Because by time HDF5 gets the data there is no overflow for your first
two array values. Using `double' should fix the problem because it can
represent all 32 bits of an `int'.
--
Robb Matzke L-159 | Ph: 812-967-6325 | I/O, I/O, it's off to disk we go,
Lawrence Livermore | Fax: 812-967-6326 | A gigabyte to read or write,
National Laboratory | Hrs: 3am-11am PDT | I/O, I/O.
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