What does a = b+c ~= d/e mean?

Hi!

I have a situation in my code like this:

a = b+c ~= d/e;

where a, b, c, d and e are real numbers, but I don't know what this expression means...

Can you help me, please?

Thank you! :D

Answer 1

[Voss]

a = b+c ~= d/e;

for scalars b, c, d, and e, is the same as

if b+c ~= d/e
     a = true;
else
     a = false;
end

[Walter Roberson]

Note that ~= has a low priority, so the code is interpreted as

(b+c) ~= (d/e)

[Laura Costa Pereira Miranda]

Thank you Voss and Walter for the answers!

But, in this case, if a is true (or false), a will have just this binary value? Because, when I display the value of a, this variable assumes a real value.

I'm still confuse about it.

And thank you a million for the answers! <3

[Voss]

Yes, a will be either true or false. a will be a logical scalar.

https://www.mathworks.com/help/matlab/matlab_prog/fundamental-matlab-classes.html

When you display a, true is represented as a 1 and false is represented as a 0:

a = true

a = logical
   1

a = false

a = logical
   0

But notice they are of class logical, not double (or some other numeric class).

However, if you use a in a calculation, the value 0 or 1 will be used:

a = true;
result = a+4 % true+4 is interpreted as 1+4

result = 5

a = false;
result = false*8 % false*8 is interpreted as 0*8

result = 0

and result is of class double (the default numeric class):

class(result)

ans = 'double'

[Laura Costa Pereira Miranda]

Oh! I understand now! It makes sense :D

Thanks a million!!

[Voss]

You're welcome!

[Walter Roberson]

By the way, in the context of if or while then an expression is considered true if the expression evaluates to something that is all non-zero (if it evaluates to contain nan then you will get an error)

if -3:2:5; disp('yep okay'); else disp('nope'); end

yep okay

if -4:2:4; disp('yep okay'); else disp('nope'); end

nope

The first one is completely non-zero but the second one contains at least one zero.