Error due to not enough input arguments in ' C_c = cold.m_dot_c*Cold.c_p_c; %W/K '

function [ q, e, UA, T_c_o ] = find_UA( hot, cold )
%Determine minimum heat capacity rate
C_c  = cold.m_dot_c * cold.c_p_c; %W/K
C_h  = hot.m_dot_h * hot.c_p_h; %W/K 
C_min   = min(C_c, C_h);
C_max   = max(C_c, C_h);

Answer 1

[Voss]

The function find_UA expects two inputs. If you provide fewer than two inputs (e.g., by clicking the green Run button in the MATLAB editor, which runs the function with zero inputs), then you will encounter this error.