how to find the equivalent resistance of two resistors in parallel and series

help me finding the equivalent resistance of two resistors for example r1 and r2 in parallel and series

clc;
clear all;
r1=1200;
r2=1000;
rt=parallel(r1,r2);
display('rt')

when i run this code i am getting either answer ams as 1 or some error

[Stephen23]

What is parallel ?

Answer 1

[dbmn]

parallel might not be the best function to use here. See more in the documentation (which is what you should do everytime you use a function either by typing help parallel or doc parallel)

sys = parallel(sys1,sys2) 
% Which needs sys, sys1 and sys2 in a state space notation to work

but why bother writing these in that special state space notation when you can simply use Wikipedia and Google

rt = r1*r2 / (r1+r2);

Answer 2

[Andrei Bobrov]

r1=1200;
r2=1000;
parallel = @(r1,r2)1/sum(1./[r1,r2]); % or: parallel = @(r1,r2)prod([r1,r2])/sum([r1,r2]);
rt=parallel(r1,r2)