# MATLAB: I am unable to understand how to execute this code.

clear alln = input('enter the value of no. of day');% t = input('enter the value of time');H = input ('enter the altitude');CF = input ('enter the fraction of cloud present');V_wind = input ('enter the value of velocity of wind');% clear t%%Constants takenu = [7.447323    2.071808    9.010095    7.981491 194];a = u(1); % 7.447323;b = u(2); % 2.071808;c = u(3); % 9.010095;d = u(4); % 7.981491;l = u(5); % 194;%%Profilex = (0:0.1:u(5));f = 1/8.*(sqrt(u(1).*(u(5)-x).*(u(2).*x-u(5)*sqrt(u(3))+sqrt(u(3)*u(5).^2-u(4)*u(5).*x))));D = 2*max(f);R = D/2;clear x%%Area of Surfacesyms x y = 1/8*(sqrt(u(1)*(u(5)-x).*(u(2).*x-u(5)*sqrt(u(3))+sqrt(u(3)*u(5).^2-u(4)*u(5).*x))));   % Given curve for shapey1 = diff(y);y2 = sqrt(1+y1.^2);y3 = y*y2;A = 2*pi*int(y3,0,u(5));vpa(A,5)                                                        % Area of EnvelopeA = ansm = 120*10.^-3*A*0.12*10.^-3clear x y%%constantsalpha = 0.15;albedo_ground = 0.35;albedo_cloud = 0.5;P_sea = 101325;e = 0.0167;%%solar modelsyms tdelta = 23.45.*sin((pi/180).*(360/365).*(284+n));% [T_oa, P_oa, rho_oa]  = atmos(H);P_oa = 5446;rho_oa = 0.088;T_oa = 216.65;w = 15.*(12-t);phi = 18.975;theta = asin(sin((pi/180).*delta).*sin((pi/180).*phi)+cos((pi/180).*delta).*cos((pi/180).*phi).*cos((pi/180).*w));% psi = asin((sin(pi/180).*w).*cos((pi/180).*delta)/cos(theta));MA = 2.*pi.*n/365;M = (P_oa/P_sea).*(sqrt(1229+(614.*sin(theta)).^2)-614.*sin(theta));  %call funTau_atm = 0.5.*(exp(-0.65.*M)+exp(-0.95.*M));zita = MA+2.*e.*sin(M)+1.25.*e.^2.*sin(2.*M); ID = (1367.*Tau_atm.^M).*((1+e.*cos(zita))./(1-e.^2)).^2;I_d = (1/2).*ID.*sin(theta).*(1.-Tau_atm.^M)./(1.-1.4.*log(Tau_atm));Q_D = alpha.*ID.*sin(theta)                                  % direct radiation% diffuse soalr radiation modelQ_d = alpha.*I_d%Reflected solar radiation modelalbedo = albedo_ground.*(1-CF).^2+albedo_cloud.*CF;Ir = albedo.*(ID.*sin(theta)+I_d);omega = pi.*abs(12-t)/12; Q_r = alpha.*Ir.*cos(omega)%Infrared Radiation from earthT_g = 280;                                                 %temperature of ground in kT_cl = 262.15;                                             % assuming cloud at altitude 4km in kR = 6371000;                                               %redius of earthepsilon_e = 0.95;      alpha_ir = 0.85;sigma = 5.67.*10.^-8;tau_atm_IR = 1.716-0.5.*(exp(-0.65.*P_oa/P_sea) + exp(-0.95.*P_oa/P_sea));T_e = T_g.*(1-CF)+T_cl.*CF;eta = asin(R/(R+H));VF = (1-cos(eta))/2;Q_earth = sigma.*epsilon_e.*alpha_ir.*VF.*tau_atm_IR.*T_e.^4%Infrared Radiation from skyPw = 0.0042;  epsilon_sky = 1;T_sky = T_oa.*(0.51+0.208.*sqrt(Pw)).^0.25;Q_sky = sigma.*epsilon_sky.*alpha_ir.*(1-VF).*T_sky.^4%Infrared Radiation from airshipsyms T_fepsilon_f = 0.85;Q_a = 2.*sigma.*epsilon_f.*T_f.^4r = 0.05;Q_aIR = alpha_ir.*sigma.*epsilon_f.*T_f.^4/(1-r)% Convection heat transfer model% external convectiong = 9.81;K_air = 0.0241.*(T_oa/273.15).^0.9;beta_air = 1/T_oa;Pr_air = 0.804-3.25.*10.^(-4).*T_oa;nu_air= 1.46.*10.^-6.*T_oa.^1.5/(rho_oa.*(T_oa+110.4));Ra_air = g.*beta_air.*(T_f-T_oa).*D.^3/nu_air.^2.*Pr_air;Re_air = V_wind.*l/nu_air;h_free = (K_air/D).*(0.6+0.387.*((Ra_air)/(1+(0.559/Pr_air).^(9/16)).^(16/9)).^(1/6)).^2;h_forced = (K_air/l).*(Re_air.*Pr_air.*(0.2275/(log(Re_air)).^2.584-850/Re_air));h_oc = (h_free.^3 + h_forced.^3).^(1/3);Q_oc = h_oc.*(T_f-T_oa)% %internal convection% syms T_he% rho_he = 0.1786% k_he = 0.144.*(T_he/273.15).^0.7% Pr_he = 0.729-1.6.*10.^(-4).*T_he% beta_he = 1/T_he% nu_he = 4.32.*10.^-6.*(T_he.^0.674)/rho_he% Ra_he = g.*beta_he.*(T_f-T_he).*D.^3/nu_he.^2.*Pr_he% if Ra_he<1.5.*10.^8%     Nu_ic = 2.5.*(2+0.6.*Ra_he.^(1/4))% else Nu_ic = 0.325.*Ra_he.^(1/3)% end%     % h_ic = Nu_ic.*k_he/D % Q_ic=h_ic.*(T_f-T_he)%%solutionC_p = 1.42;h = 1;x = 0:h:23y = zeros(1,length(x))y(1) = 216.65F_xy = (Q_D+Q_d+Q_r+Q_earth+Q_sky-Q_aIR-Q_a-Q_oc)/(m.*C_p)for i=1:(length(t))                              % calculation loop    k_1 = F_xy(x(i),y(i))    k_2 = F_xy(x(i)+0.5.*h,y(i)+0.5.*h.*k_1)    k_3 = F_xy((x(i)+0.5.*h),(y(i)+0.5.*h.*k_2))    k_4 = F_xy((x(i)+h),(y(i)+k_3.*h))      y(i+1) = y(i) + (1/6).*(k_1+2.*k_2+2.*k_3+k_4).*h  % main equation  end