MATLAB - how to create condition with specific requirements

Question

I'm simulating water heating and I need to create certain condition and I dont know how to create it properly.

Required temperature of water is 55 °C. Minimal temperature is 50 °C. Maximum temperature is 70 °C.

I have 2 types of heating - electrical heating which heats water to required temperature 55 °C and photovoltaic heating which can heat water to maximum temperature.

I need to create condition which turn on electrical heating only if temperature drops below 50 °C and stops after reaching 55 °C. If the temperature is between 50 and 55 without previously dropping under 50 °C only photovoltaic heating is possible and electrical heating is off.

Temperature is checked every minute for whole year. Conditions will be placed in for cycle.

Right now, I have it without condition for required temperature (55 °C) like this:

for i = 1:525600
    if (temeprature(i) < 70)
           heating = 1; %heating from photovoltaic
       else
           heating = 0; % heating off
       end
         if (temperature(i) < 50)
          heating = 2; % electric heating when there is not enough power from PV                   
         end
   if heating==0
     calculations
     calling functions
     etc.
     ...
    end
   if heating==1
     calculations
     calling functions
     etc.
     ...
    end 
   if heating==2
     calculations
     calling functions
     etc.
     ...
    end 
 computing temperature with results from conditions
 end

Thanks for any advice.

Answer 1

I would make a function with persistent variable for electric heating:

function [el, pv] = whatHeating(T)
persistent elHeat
if (isempty(elHeat))
    elHeat = false; % Initialize to false. The only thing where it matters is if you start at 50<T<55.
end

if (T < 50)
    elHeat = true;
elseif (T > 55)
    elHeat = false;
end
el = elHeat; % You can't return persistent variable directly.

if (T > 70)
    pv = false;
else
    pv = true;
end

Then you simply call this function in your main one.