check if a variable has real or complex entries
t=isreal(x)
t=isreal(x,eps)
:x vector or matrix with floating point entries or coefficients : :t a boolean :
isreal(x) returns true if x is stored as a real variable and false if x is stored with an (eventually zero) imaginary part.
isreal(x,eps) returns true if x is stored as a real variable or if maximum absolute value of imaginary floating points is less or equal than eps.
isreal([1 2])
isreal(1+0*%i)
isreal(1+0*%i,0)
isreal(1+%s)
isreal(`sprand`_(3,3,0.1))