Multimeter in a Wheatstone Bridge

%% Multimeter in a Wheatstone Bridge
% Calculate the magnitude of the voltage when the multi-meter is set to
%   voltmeter and the current when in ammeter mode. Notes and clarifications
%   are at the end

% Inputs and Variables
R = input('Enter the resistances of resistors 1-4 in brackets\n');
E = input('Value of E in volts\n');

% Outputs and Equations
mag = E*((R(2)*R(3)-R(1)*R(4))/((R(2)+R(1))*(R(3)+R(4))));
c = R(1)*R(3)/(R(1)+R(3));
d = R(2)*R(4)/(R(2)+R(4));
i = E/(c+d);
i1 = i*c/R(1);
i2 = i*d/R(2);
ia = i1-i2;
fprintf('The magnitudes in voltmeter and ammeter mode are :\n %.03f V and %.3e A \n', mag, ia);

%{
When the user inputs the resistances they have to be in brackets [] otherwise
    the code will not work.
Usually variables will have interesting names so that the user will be able to
    follow along. However, there was a lot of different steps to solve the
    equation so variables 'c' and 'd' are just place holders so that the code
    wasn't too clutter in each line.

%}