CAN SOMEONE EXPLAIN ME THIS CODING PLEASE ?

I can't understand what this coding is trying to do...

function thermal_boundary
clc
clear all
close all
x=0;
x=4;
xl=fzero(@eqsol,x)

%%Parameters of Blasius Equation
U_inf = 1;
L = 10;
mu = 1.789E-5;
rho = 1.225;
nu = mu/rho;
A = sqrt(nu/U_inf);
h = 0.01;
%%Numerical Solution of Blasius Equation 
dq1 = @(x, r1, r2, r3) r2;
dq2 = @(x, r1, r2, r3) r3;
dq3 = @(x, r1, r2, r3) -r1*r3;
eta = 0:h:10;
x = 0:h:10;
r1(1) = 0;
r2(1) = 0;
r3(1) = 0.4696;
for i = 1:(length(eta)-1)
a = h.*[dq1(eta(i), r1(i), r2(i), r3(i)), dq2(eta(i), r1(i), r2(i), r3(i)), dq3(eta(i), r1(i), r2(i), r3(i))];
b = h.*[dq1(eta(i), r1(i)+a(1)/2, r2(i)+a(2)/2, r3(i)+a(3)/2), dq2(eta(i)+h/2, r1(i)+a(1)/2, r2(i)+a(2)/2, r3(i)+a(3)/2), dq3(eta(i)+h/2, r1(i)+a(1)/2, r2(i)+a(2)/2, r3(i)+a(3)/2)];
c = h.*[dq1(eta(i), r1(i)+b(1)/2, r2(i)+b(2)/2, r3(i)+b(3)/2), dq2(eta(i)+h/2, r1(i)+b(1)/2, r2(i)+b(2)/2, r3(i)+b(3)/2), dq3(eta(i)+h/2, r1(i)+b(1)/2, r2(i)+b(2)/2, r3(i)+b(3)/2)];
d = h.*[dq1(eta(i), r1(i)+c(1), r2(i)+c(2), r3(i)+c(3)), dq2(eta(i)+h, r1(i)+c(1), r2(i)+c(2), r3(i)+c(3)), dq3(eta(i)+h, r1(i)+c(1), r2(i)+c(2), r3(i)+c(3))];
r3(i+1) = r3(i)+ 1/6*(a(3)+2*b(3)+2*c(3)+d(3));
r2(i+1) = r2(i)+ 1/6*(a(2)+2*b(2)+2*c(2)+d(2));
r1(i+1) = r1(i)+ 1/6*(a(1)+2*b(1)+2*c(1)+d(1));
end
%%Plotting and Visualization
figure(2)
plot(eta,r1,eta, r2, eta, r3, 'LineWidth', 2)
xlim([0 10])
title('Solution of Blasius eqution', 'FontSize', 14);
xlabel('f, f'' and f''''', 'FontSize', 20);
ylabel('\eta', 'FontSize', 20);
grid on
Legend1 = {'f(\eta)', 'f''(\eta)', 'f''''(\eta)'};
legend(Legend1, 'FontSize', 14);

function d=eqsol(x)

options=odeset('RelTol',1e-8,'AbsTol',[1e-8 1e-8]);
[a,b]=ode45(@eqsoll,[0,20],[0 x],options);
c=length(a);
d=b(c,1)-1;
figure(1)
plot(a,b(:,1))
xlabel('Temperature', 'FontSize', 15);
ylabel('\eta', 'FontSize', 20);
grid on
hold on;
end
end

function d_y=eqsoll(t,y)
d_y=zeros(2,1);
d_y(1)=y(2);
d_y(2)=-(0.71*18.2792*y(2)/2);
end

[Vetrichelvan Pugazendi]

function thermal_boundary1
clc
clear all
close all
x=0;
x=4;
xl=fzero(@eqsol,x)

%%Parameters of Blasius Equation
U_inf = 1;
L = 10;
mu = 1.789E-5;
rho = 1.225;
nu = mu/rho;
A = sqrt(nu/U_inf);
h = 0.01;
%%Numerical Solution of Blasius Equation 
dq1 = @(x, r1, r2, r3) r2;
dq2 = @(x, r1, r2, r3) r3;
dq3 = @(x, r1, r2, r3) -r1*r3;
eta = 0:h:10;
x = 0:h:10;
r1(1) = 0;
r2(1) = 0;
r3(1) = 0.4696;
for i = 1:(length(eta)-1)
a = h.*[dq1(eta(i), r1(i), r2(i), r3(i)), dq2(eta(i), r1(i), r2(i), r3(i)), dq3(eta(i), r1(i), r2(i), r3(i))];
b = h.*[dq1(eta(i), r1(i)+a(1)/2, r2(i)+a(2)/2, r3(i)+a(3)/2), dq2(eta(i)+h/2, r1(i)+a(1)/2, r2(i)+a(2)/2, r3(i)+a(3)/2), dq3(eta(i)+h/2, r1(i)+a(1)/2, r2(i)+a(2)/2, r3(i)+a(3)/2)];
c = h.*[dq1(eta(i), r1(i)+b(1)/2, r2(i)+b(2)/2, r3(i)+b(3)/2), dq2(eta(i)+h/2, r1(i)+b(1)/2, r2(i)+b(2)/2, r3(i)+b(3)/2), dq3(eta(i)+h/2, r1(i)+b(1)/2, r2(i)+b(2)/2, r3(i)+b(3)/2)];
d = h.*[dq1(eta(i), r1(i)+c(1), r2(i)+c(2), r3(i)+c(3)), dq2(eta(i)+h, r1(i)+c(1), r2(i)+c(2), r3(i)+c(3)), dq3(eta(i)+h, r1(i)+c(1), r2(i)+c(2), r3(i)+c(3))];
r3(i+1) = r3(i)+ 1/6*(a(3)+2*b(3)+2*c(3)+d(3));
r2(i+1) = r2(i)+ 1/6*(a(2)+2*b(2)+2*c(2)+d(2));
r1(i+1) = r1(i)+ 1/6*(a(1)+2*b(1)+2*c(1)+d(1));
end
%%Plotting and Visualization
figure(2)
plot(eta,r1,eta, r2, eta, r3, 'LineWidth', 2)
xlim([0 10])
title('Solution of Blasius eqution', 'FontSize', 14);
xlabel('f, f'' and f''''', 'FontSize', 20);
ylabel('\eta', 'FontSize', 20);
grid on
Legend1 = {'f(\eta)', 'f''(\eta)', 'f''''(\eta)'};
legend(Legend1, 'FontSize', 14);

function d=eqsol(x)

options=odeset('RelTol',1e-8,'AbsTol',[1e-8 1e-8]);
[a,b]=ode45(@eqsoll,[0,20],[0 x],options);
c=length(a);
d=b(c,1)-1;
figure(1)
plot(a,b(:,1))
xlabel('Temperature', 'FontSize', 15);
ylabel('\eta', 'FontSize', 20);
grid on
hold on;
end
end

function d_y=eqsoll(t,y)
d_y=zeros(2,1);
d_y(1)=y(2);
d_y(2)=-(0.71*18.2792*y(2)/2);
end

[Geoff Hayes]

Vetrichelvan - where did you get this code? Why don't you ask the author?

Answer 1

[Steven Lord]

Have you asked the person who provided that code to you for an explanation?

If the person who provided the code to you is unwilling or unable to provide an explanation, or you downloaded this off the internet, your best bet is probably going to be walking through the code, line by line or section by section, determining what each line or section of code does.

Add comments to the code as you determine the purpose of each line or section (and add questions that you think you'll need to look at later sections of the code to answer.) If you're not sure what a particular function does, look at the doc for that function (if it's a MathWorks function.)

If after doing that you have a specific question about the purpose of a specific segment of that code, ask that specific question here and we may be able to provide some guidance.