time looping or increment not updating

Hi all,

I have to time loop/time increment with the code: t=deltat:deltat:3600*5;

Even by varying the time t in the for loop I could not find any change. Please suggest me whether the time looping which I had mentioned is correct or else I have to follow some other steps.

When I plot with the output value of F vs -Z at any time I get the same ans. Simila case with plot u vs -Z.

Please help me in time looping/incrementing. Thank you in advance

    alpha=(17*pi)/180;        %slope angle  
    dz=200;         %depth of water table from the suface
    dlz=400;        % toltal depth of slope  
    fi=(25*pi)/180;          %friction angle  
    C=0.004;          %4 kpa=0.4 N/cm^2  
    gsat=0.021;      %21 kN/m^3
    gw=0.0098;       %9.81 Kn/m^3
    Dzero=4;        %0.0004m^2/s
    ksat=1e-3;      %e-5 m/s
    iz=2e-4;        %iz=7.2 mm/h= 2e-4 cm/s
    deltat=10;      %time step
    deltaz=0.8;     %space step
    T=12*60*60;     %time duration of rainfall= 12h to seconds
    e=(deltat/deltaz^2)*Dzero*cos(17*pi/180)*cos(17*pi/180);
    n=500;          % number of nodes
    nt=4320;        %time step, based on T
    Z=linspace(deltaz,400,500);     %Depth in cm  
       %Setup sparse matrix
           si=(Z-dz)*cos(alpha)*cos(alpha); %Initial condition ...i.e.
        %pressure head @t=0 all along the depth
      if true
        % code
      end
    si=si';
    a=-e*ones(n,1); % lower Triagonal vectors
    % a(1)=0; a(n)=-114.314; a=a';
    b=116.314*ones(n,1);  % Diagonal vectors
    b=b';
    c=-e*ones(n-1,1);% Upper trigonal vector
    % c(1)=-114.314;  c(n)=0; c=c';
    d=ones*(n-2:1);
    for t=deltat:deltat:3600*5;
        for w=2:499
        d(w)=e*si(w-1)-112.314*si(w)+e*si(w+1); % Rhs vector
        end
        if t>T
    d(1)=-112.314*si(1)+114.314*si(2)-130.686;
    else
    d(1)=-112.314*si(1)+114.314*si(2)-167.264;  % t<=T
        end
        d(500)=114.314*si(499)-112.314*si(500)+167.264; % Boundary condition...
    %at the bottom of the slope at all values of t
    end
    A=ones*(n-1:1);
    S=ones*(n-1:1);
    d=d';
    A(1)=b(1);               % A(1)=alpha one=b(1)  
    S(1)=d(1);               % S(1)=Rhs(1)   
    for i=2:n %varies from 2 to n
        A(i)=b(i)-((a(i)/(A(i-1))*c(i-1)));
        S(i)=d(i)+((a(i)/(A(i-1))*S(i-1)));
    end
    A=A';
    S=S';
    u(n)=S(n)/A(n); %u(N-1)=S(N-1)/A(N-1), "M*u=S", solve for u with M known...
    % ... trigonal matrix and S= known Rhs vector
     for t=deltat:deltat:3600*18;
       for j=n-1:-1:1
       % for w=10:10:4320
        u(j)=(1/A(j))*(S(j)+(c(j)*u(j+1)));
       end
    end
    %  disp([t u]);
     u=u';
    if u(1)<=0 %Check for ponding 
    Fs=(tan(fi)/tan(alpha))*ones(n,1);  %Gravity component
    Fs=Fs';
    Fw=(-u*gw*tan(fi))./(gsat*Z'*sin(alpha)*cos(alpha)); %Water pressure ...
    %component
    Fw=Fw';
    Fc=C./(gsat*Z'.*sin(alpha)*cos(alpha)); %Cohesion component
    Fc=Fc';
    F=Fs+Fw+Fc; %FOS for slope
    elseif soln(1)<=0 && (t<T)
        d(1)=-114.314*si(1)+114.314*si(2)-130.686;
    elseif soln(1)>0 &&(t<T)
        soln(1)=0;
    else
        d(1)=-114.314*si(1)+114.314*si(2)-167.264;
    end
    Fs=(tan(fi)/tan(alpha))*ones(n,1);  %Gravity component
    Fs=Fs';
    Fw=(-u*gw*tan(fi))./(gsat*Z'*sin(alpha)*cos(alpha)); %Water pressure ...
    %component
    Fw=Fw';
    Fc=C./(gsat*Z'.*sin(alpha)*cos(alpha)); %Cohesion component
    Fc=Fc';
    F=Fs+Fw+Fc; %FOS for slope
    if true
      % code
    end

[Geoff Hayes]

When you say Even by varying the time t in the for loop I could not find any change, which t are you varying? t is an index in the for loop, so that can't be it. Is it the deltat that you are changing, and if so, to what?

[Stephen23]

As an aside, you should avoid naming variables i and j, as these are the inbuilt imaginary unit . Accidentally overloading inbuilt functions and variables can cause all sorts of very-difficult-to-figure-out problems later...

Answer 1

[Star Strider]

I didn’t run your code, but it seems that none of your variables inside either of your ‘t’ loops are actually functions of ‘t’. They simply loop endlessly over the same values.

[Star Strider]

advaita vedanta’s ‘Answer’ moved here:

 @Star strider, yes what you mentioned I agree, I am confused on how to assign.

Thank you

[Star Strider]

What are your original functions?

How are they functions of time?

Answer 2

[advaita vedanta]

@Geoff Hayes, I am mentioning time t, actually I want to know the output (u,F) for different values of time t, which I had mentioned in the for loop [not deltat). please correct me. Thank You