How to comparison decimal numbers
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Hi all!
I have two matrices. They have one column. First matrix is:
7.551119
7.551154
7.551189
7.551224
Second matrix is:
7.551111
7.551146
7.551181
7.551215
I want to comparison two columns but only 5 decimal places. I don't like round my numbers like:
7.55112
7.55115
and so on, if I use the function round.
2 Commenti
Walter Roberson
il 1 Dic 2015
When you say that you want to compare to 5 decimal places, do you mean that when printed out rounded to 5 decimal places the numbers must match, or do you mean that the difference between the two numbers must be less than 10^(-5) ? Or at most 1/2 * 10^(-5) ?
Risposta accettata
arich82
il 2 Dic 2015
You can truncate (without rounding) using floor (or fix, if your numbers can be negative):
x = [ ...
7.551119; ...
7.551154; ...
7.551189; ...
7.551224; ...
];
y = fix(x*1e5)/1e5;
output:
y =
7.551110000000000
7.551150000000000
7.551180000000000
7.551220000000000
Più risposte (2)
Image Analyst
il 2 Dic 2015
You need to use a tolerance. See the FAQ for a complete explanation: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
0 Commenti
Thorsten
il 2 Dic 2015
Modificato: Thorsten
il 2 Dic 2015
You can round to 5 decimal places using
xr = round(x*1e5)/1e5;
You may want to set
format long
such that the result is properly displayed.
5 Commenti
Image Analyst
il 2 Dic 2015
Then don't round (as I suspected you shouldn't). Use the tolerance like I told you in my answer where I referred you to the FAQ.
Walter Roberson
il 2 Dic 2015
To check, Thodoris, you are okay with 7.551111 comparing equal to 7.551119, but 7.551119 should not compare equal to 7.551121 even though that is closer to it than 7.551111 is?
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