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When I import data from a .dat file, V11.3 emits the message: is too small to represent as a normalized machine number; precision may be lost.

How can I close the display or replace the offending number with 0.?

Here is my code:

ReadList[OpenRead["C:\\Users\\px\\Desktop\\1.DAT"], Real]

I know Import will not show this warning, but its speed is slow.

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  • 3
    $\begingroup$ You can use Quiet[] of course, but this just hides problems. Can you post a sample .dat file that is triggering this warning? $\endgroup$ – J. M. will be back soon Mar 31 at 13:48
  • $\begingroup$ Except for you, no one else has the file 1.DAT. How do you expect to get help if you don't post that file? $\endgroup$ – J. M. will be back soon Mar 31 at 14:06
  • $\begingroup$ @J. M. is slightly pensive Sorry, I don't ’how to upload attachments $\endgroup$ – xin pei Mar 31 at 14:08
  • $\begingroup$ Copy the contents of 1.DAT, go to Pastebin, post the contents there, and then post a link here. $\endgroup$ – J. M. will be back soon Mar 31 at 14:09
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    $\begingroup$ $MinMachineNumber is 2.22507*10^-308 (Windows 10, Mathematica 10.4). Your dataset has 9 out of 15580 numbers between 1.094829709000000*10^-318and 1.319006165000000*10^-316. If it is appropriate you could modify the data or maybe the following would be helpful: mathematica.stackexchange.com/questions/161031/…. $\endgroup$ – JimB Mar 31 at 14:48
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If we multiply the exponents by, say, 10^20, then the data will fall within machine-precision range. There may be a more natural way to rescale (based on units, for instance), but we have only raw numbers to work with. (One can also convert the mantissas to arbitrary-precision number before multiplying by the exponent; however, I suspect that machine numbers are to be preferred.)

data = #1*10.^(#2 + 20) & @@ Transpose[
     ToExpression[
      StringSplit[#, "E"] & /@
       (raw = Import["https://pastebin.com/raw/gkB6zKVC", "Table", "Numeric" -> False])
      ],
     {2, 3, 1}]; // AbsoluteTiming
(*  {0.216465, Null}  *)

Some checks. There are some rounding differences between the imported data and the converted data.

Dimensions@data
Dimensions@raw
(*
  {76, 205}
  {76, 205}
*)

Quiet@Block[{Indeterminate = 0},
  Import["https://pastebin.com/raw/gkB6zKVC", "Table"]/data // 
    Flatten // DeleteDuplicates
  ]
(*
{0, 1.0000000000000001`*^-20, 1.0000000000000002`*^-20, 
    9.999999999999998`*^-21,  9.999999996284607`*^-21, 
    9.99999999915014`*^-21,   1.0000000000496418`*^-20, 
    1.0000000001289331`*^-20, 1.0000000002912905`*^-20, 
    1.000000000045069`*^-20,  9.999999995966217`*^-21, 
    1.0000000002256684`*^-20, 9.99999999965454`*^-21} 
*)
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