Bioequivalence and Bioavailability Forum

From bad to worse [Software]

posted by Ohlbe – France, 2020-12-10 23:11 (1372 d 20:19 ago) – Posting: # 22133
Views: 10,763

Hi fellows,

Sorry guys, but there are some things going back behind the scene, which I really fail to understand.

If I get -2,77556E-17 when I type =(0.5-0.4-0.1), how comes that I get 0 when I type =(-0.1-0.4+0.5) ? The same figures, just in a different order ?

If I get FALSE when I type =0=0.5-0.4-0.1, how comes that I get TRUE when I type =0=-0.4-0.1+0.5 ?

And to be fair to Excel, the same happens in :

0==(0.5-0.4-0.1)
[1] FALSE
0==(-0.4-0.1+0.5)
[1] TRUE

Are they first calculating -0.4-0.1=-0.5, which is nicely binarily coded, then -0.5+0.5=0 ?

Complete thread:

• Spreadsheet failures, any recent examples? ElMaestro 2019-07-18 13:43 [Software] 
  • Spreadsheet failures, any recent examples? Ohlbe 2019-07-18 14:32
    • Spreadsheet addiction Helmut 2019-07-18 16:12
      • Nasty beast Ohlbe 2019-07-18 17:30
        • Nasty beast Helmut 2019-07-18 20:26
          • Nasty beast Ohlbe 2019-07-19 11:32
            • Nasty beast ElMaestro 2019-07-19 12:32
              • Decidedly off topic Ohlbe 2019-07-19 13:38
            • OT: R limbo 101 Helmut 2019-07-19 13:00
      • Spreadsheet addiction Shuanghe 2019-07-18 18:59
        • Spreadsheet addiction Helmut 2019-07-18 20:04
          • OT: Spreadsheet addiction Shuanghe 2019-07-19 12:41
            • OT: Spreadsheet addiction Helmut 2019-07-19 14:29
              • OT: Spreadsheet addiction nobody 2019-07-19 15:53
                • OT: Spreadsheet addiction Helmut 2019-07-19 19:32
    • Spreadsheet etc. failures zizou 2019-07-20 00:18
      • As designed ☺ Helmut 2019-07-20 02:12
        • As designed ☺ ElMaestro 2019-07-20 09:08
          • To round or not to round… Helmut 2019-07-20 12:53
            • To round or not to round… ElMaestro 2019-07-20 19:59
              • floating-point math is always more complex than you think it is mittyri 2019-07-20 22:43
  • Spreadsheet failures, any recent examples? Ohlbe 2020-12-10 18:43
    • Floating point arithmetic, again Helmut 2020-12-10 19:12
      • Floating point arithmetic, again ElMaestro 2020-12-10 19:40
        • Floating point arithmetic, again Ohlbe 2020-12-10 20:18
          • Floating point arithmetic, again ElMaestro 2020-12-10 21:38
            • Floating point arithmetic, again Ohlbe 2020-12-10 21:46
              • Floating point arithmetic, again ElMaestro 2020-12-10 22:05
                • Depressed Ohlbe 2020-12-10 23:35
                  • Depressed ElMaestro 2020-12-11 07:59
      • Floating point arithmetic, again Ohlbe 2020-12-10 20:13
    • From bad to worseOhlbe 2020-12-10 22:11
      • From bad to worse mittyri 2020-12-11 00:22
      • All is good Helmut 2020-12-11 00:36
        • Float is float PharmCat 2020-12-18 20:53
          • Float is float! Helmut 2020-12-20 23:27
            • rational solution in R mittyri 2020-12-21 13:49
              • related stuff Helmut 2021-01-14 12:53
                • related stuff SDavis 2021-02-09 12:02
                  • related stuff ElMaestro 2021-02-09 19:55