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I know in C language, for any number x using x%2 will calculate the remainder when x is divided by 2, which will help decipher whether its even or not.

How can I do this in matlab?

Steven Lord
on 9 Oct 2020

So Inf is even?

>> s = (-1)^Inf

s =

1

How about NaN?

>> s = (-1)^NaN

s =

NaN

Does this hold for a complex number as well?

>> N = 3+4i;

>> s = (-1)^N; % Not equal to -1

Walter Roberson
on 23 Oct 2012

Edited: MathWorks Support Team
on 9 Nov 2018

Dillen.A
on 5 Feb 2020

A quick example:

A = [-2 -1 0 1 2 3 4 5 6]; % A is your value or matrix

IS_EVEN = ~mod(A,2)

Which is the same as

IS_EVEN = ~bitget(abs(A),1)

And the same as

IS_EVEN = ~rem(A,2)

You can use logical() instead of ~ (isnot) for ODD, should you want booleans. Also bitget() does not work for negative integers, hence abs().

A warning though; ONLY bitget() will throw an error if an element in A is not an integer! the others will output 'odd' for fractions.

Unless you will repeat this many many times, the speed is not relevant. Otherwise, you should vectorize.

Matt J
on 23 Oct 2012

if bitget(A,1) %odd

else %even

end

Josh Meyer
on 10 Oct 2018

In more recent versions of MATLAB, bitmax was replaced by flintmax. This is the largest consecutive floating point number. After flintmax, the value of eps is larger than 1 (slowly increasing in powers of 2), so representable numbers larger than flintmax are no longer consecutive.

So, the reason all of those numbers are even is because flintmax is an even number and the spacing between numbers is eps(flintmax) = 2.

Ibn e Adam
on 18 Feb 2020

% function to find even/odd

% n is input number for this function

function output=even_or_odd(n)

if rem(n,2)==0

output=even;

else

output=odd;

end

end

Anmol singh
on 10 Apr 2020

Edited: Anmol singh
on 10 Apr 2020

A givennumber is even or odd for this we use & operator.

if any number is odd it must have right most bit 1.

example:

int i=5;

binary form i= 0101

now use & operator

int j=i&1;[0101&1]//

here j have 0001;

Walter Roberson
on 10 Apr 2020

This does not work in MATLAB. In MATLAB, the operation

c = A & B

is equivalent to

if A ~= 0

if B ~= 0

c = true;

else

c = false;

end

elseif B ~= 0

c = false;

else

c = false;

end

Yes, this could be made more efficient, but this models the & operator. The more efficient operation is &&

Now notice that this is not a bitwise operation. 5&1 is not binary 0101 & 0001 giving 0001: instead it is (5~=0) and (1 ~= 0)

The MATLAB equivalent to what you are discussing is the bitand() operator

bitand(5,1)

But if you are going to do that, you might as well just ask for the last bit directly:

bitget(5,1) %the 1 is a bit number with LSB being #1

luis fonseca
on 9 Oct 2020

This is the easiert way guys, its just math from highschool

N = 1; % number you want to know if even or odd

%% create an expression

s = (-1)^N;

%% if s = -1, the N is odd, else N is even

if s == -1

disp('N is odd')

else

disp('N is even')

end

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