Logical Functions

allof(x)    returns 1 if every element of x is non-zero 
anyof(x)    returns 1 if any element of x is non-zero 
noneof(x)   returns 1 if no element of x is non-zero 
nallof(x)   returns 1 if any element of x is zero

where(x)    returns list of indices where x is non-zero 
where2(x)   human-readable variant of where