Getting error Operands to the || and && operators must be convertible to logical scalar values.

I have to check the arguments of my function for a number of cases. The function passes all tests besides the arguments

12, 3, [3 4], 5

The code is as follows

function dd= day_diff(month1, day1, month2, day2)
if month1<1 || month2<1 || day1<=0|| day2<=0 || rem(month1,1)~=0 ||rem(day1,1)~=0 ||  rem(month2,1)~=0 || rem(day2,1)~=0 || isscalar(month1)~=1 || isscalar(month2)~=1 || isscalar(day1)~=1 || isscalar(day2)~=1 
    dd=-1;
elseif (month1==2 && day1==29) || (month2==2 && day2==29)
     dd=-1;
elseif (eomday(2015,month1)==30 && day1==31) ||(eomday(2015,month2)==30 && day2==31)
    dd=-1;

The error I get

>> day_diff(12, 3, [3 4], 5)
Operands to the || and && operators must be convertible to logical
scalar values.

Error in day_diff (line 2)
if (month1<1 || isscalar(month1)~=1) || (month2<1
||isscalar(month1)~=1) ||  day1<=0|| day2<=0 || rem(month1,1)~=0
||rem(day1,1)~=0 ||  rem(month2,1)~=0 || rem(day2,1)~=0 ||
isscalar(day1)~=1 || isscalar(day2)~=1

Any help will be appreciated.

Answer 1

[Star Strider]

The short-circuit operators don’t work with vector arguments. Replace them with single ‘|’ and ‘&’ and see if that solves the problem.

Answer 2

[Steven Lord]

month2 = [3 4];
z = month2 < 1

Is z a logical scalar value? In order to be a logical scalar value, it must be BOTH logical (check this with the class function) AND scalar (check with isscalar.)

Reorder your error checking to check that the input are scalar first. Once you know your inputs are scalar, then you can check their values.

[Param Siddharth]

Thank you very much! This was indeed very helpful.