repeating a for loop

Res=input ('Enter the resistance values in ohm,R1 to Rn,values must be positive and real > ');

for i=1:1:n
if  Res(1,i)<0 | imag(Res(1,i))~=0
         Res=input ('Enter the resistance values in ohm,R1 to Rn,values must be positive and real > ');
end
end

how to make this code repeat from the begining from the bigginig if statement is true

[Bilal Bukhary]

how to make this code repeat from the begining if, Res(1,i)<0 | imag(Res(1,i))~=0 statement is true

Answer 1

[KSSV]

n = 4 ; 
for i=1:1:n
  Res(i)=input ('Enter the resistance values in ohm,R1 to Rn,values must be positive and real > ');
  while Res(i)<0
    Res(i)=input ('Enter the resistance values in ohm,R1 to Rn,values must be positive and real > ');
  end

end