Question about constraints in optimization problems

I have the following victor:

A=[ 0.1 0.1 0.3 0.2 0.3]

The sum of this vector is 1, but when I try the following code:

Test = (sum(A(:)) ==1)
If ( Test  == 1 )
    "True"
Else
    "False"

The results is always FALSE.

What is the problem

Answer 1

[Ameer Hamza]

This is due to the finite precision of floating-point numbers. Calculations on floating points numbers can accumulate errors, so the value is not exactly equal to one. You need to allow a bit of tolerance in comparing floating-point values. For example

Test = (sum(A(:)) ==1)
if ( abs(Test-1) < 1e-6 )
    "True"
else
    "False"
end

Read more about this here: https://en.wikipedia.org/wiki/Double-precision_floating-point_format

[Walter Roberson]

See http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

[Rahim Rahim]

@Walter Roberson thank you for your comment

Any part should I see ?

[Walter Roberson]

All of the section on the topic.