Why is logical array fasle?

SCRIPT WINDOW

g=9.8000 %value for g

p=3.14; %value of mathematical pie

k1=3.1210191*p

k1==g %generation of logical array

COMMAND WINDOW

g =

9.8000

k1 =

9.8000

ans =

logical

0

Answer 1

[Scott MacKenzie]

The result is false because k1 DOES NOT EQUAL g

Note that both k1 and g are scalars, not vectors. Therefore, the result of k1==g is a logical scalar which is false or 0.

Answer 2

[Steven Lord]

Floating point arithmetic. While k1 and g are displayed the same they do not contain the same value down to the last bit.

Answer 3

[Kunal Kandhari]

It is because most decimal fractions are not exactly representable in binary form, just like 1/3 is not representable exactly in a finite number of decimal digits.

if you print 55 decimal places of both the variables you will get something like this:

sprintf('%0.55f',k1)
'9.7999999740000003356499291840009391307830810546875000000'

sprintf('%0.55f',g)
'9.8000000000000007105427357601001858711242675781250000000'

NEVER compare two floating point doubles for exact equality. Well, there are some notable exceptions. So unless you know the exceptions, then assume never applies.

You can see a very detailed description of the same here:

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