Cannot subtract number of order smaller then e-4 from variable

a=0.1; a=a-1e-5 gives result a=0.1000

Answer 1

[Torsten]

It's just a question of how the numbers are displayed.

Internally, the precision of computing is much higher.

format long  % Use display format long
a = 0.1;
a = a - 1e-5

a = 
   0.099990000000000

format short
a

a = 0.1000

[Dominik Stolfa]

Thanks.

[Walter Roberson]

format long  % Use display format long
a = 0.1;
fprintf('%.999g\n', a)

0.1000000000000000055511151231257827021181583404541015625

a = a - 1e-5

a = 
   0.099990000000000

fprintf('%.999g\n', a)

0.09999000000000000942801392511682934127748012542724609375

[Dominik Stolfa]

Thank you for nice example. I was confused before whether the Matlab changes the values at all because even after subtracting 6e-5 or so, the values were still same. I didn’t go past up to 9e-5 because I was like “what are the chances”. :D