CODEWITHSUNDEEP
matlabfor-loop
cruxsign
cruxsign

Reputation: 5

Save outputs of nested for loops in MATLAB

I have the following codes which I wish to have an output matrix Rpp of (10201,3). I run this code (which takes a bit long) then I check the matrix size of Rpp and I see (1,3), I tried so many things I couldn't find any proper way. The logic of the codes is to take the 6 values (contain 4 constant values and 2 variable values (chosen from 101 values)) and make the calculation for 3 different i1 and store every output vector of 3 in a matrix with (101*101 (pairs of those 2 variable values)) rows and 3 (for each i1) columns.

I appreciate your help

    Vp1=linspace(3000,3500,101);
    Vp2=3850;
    rho1=2390;
    rho2=2510;
    Vs1=linspace(1250,1750,101);
    Vs2=2000;
    i1=[10 25 40];


    Rpp = zeros(length(Vp1)*length(Vs1),length (i1));

    for n=1:length(Vp1)*length(Vs1)
    for m=1:length (i1)
    for l=1:length(Vp1)
        for k=1:length(Vs1)


           p=sin(i1)/Vp1(l);
           i2=asin(p*Vp2);
           j1=asin(p*Vs1(k));
           j2=asin(p*Vs2);
           a=rho2*(1-2*Vs2^2*p.^2)-rho1*(1-2*Vs1(k).^2*p.^2);
           b=rho2*(1-2*Vs2^2*p.^2)+2*rho1*Vs1(k)^2*p.^2;
           c=rho1*(1-2*Vs1(k)^2*p.^2)+2*rho2*Vs2^2*p.^2;
           d=2*(rho2*Vs2^2-rho1*Vs1(k)^2);
           E=b.*cos(i1)./Vp1(l)+c.*cos(i2)/Vp2;
           F=b.*cos(j1)./Vs1(k)+c.*cos(j2)/Vs2;
           G=a-d*(cos(i1)/Vp1(l)).*(cos(j2)/Vs2);
           H=a-d*(cos(i2)/Vp2).*(cos(j1)/Vs1(k));
           D=E.*F+G.*H.*p.^2;
           Rpp=((b.*(cos(i1)/Vp1(l))-c.*cos((i2)/Vp2)).*F-(a+d*((cos(i1)/Vp1(l))).*(cos(j2)/Vs2)).*H.*p.^2)./D
        end
    end
    end
    end

Upvotes: 0

Views: 134

Answers (2)

user3667217
user3667217

Reputation: 2192

The way you use the for loop is wrong. You're running the calculation for length(Vp1)*length(Vs1) * length (i1) * length(Vp1) * length(Vs1) times. Here's the correct way. I changed l into lll just so I won't confuse it with the number 1. In each iteration of the first for loop, you're running length(Vs1) times, and you need to assign the result (a 1X3 array) to the Rpp by using a row number specified by k+(lll-1)*length(Vp1).

for lll=1:length(Vp1)
    for k=1:length(Vs1)
       p=sin(i1)/Vp1(lll);
       i2=asin(p*Vp2);
       j1=asin(p*Vs1(k));
       j2=asin(p*Vs2);
       a=rho2*(1-2*Vs2^2*p.^2)-rho1*(1-2*Vs1(k).^2*p.^2);
       b=rho2*(1-2*Vs2^2*p.^2)+2*rho1*Vs1(k)^2*p.^2;
       c=rho1*(1-2*Vs1(k)^2*p.^2)+2*rho2*Vs2^2*p.^2;
       d=2*(rho2*Vs2^2-rho1*Vs1(k)^2);
       E=b.*cos(i1)./Vp1(lll)+c.*cos(i2)/Vp2;
       F=b.*cos(j1)./Vs1(k)+c.*cos(j2)/Vs2;
       G=a-d*(cos(i1)/Vp1(lll)).*(cos(j2)/Vs2);
       H=a-d*(cos(i2)/Vp2).*(cos(j1)/Vs1(k));
       D=E.*F+G.*H.*p.^2;
       Rpp(k+(lll-1)*length(Vp1),:)=((b.*(cos(i1)/Vp1(lll))-c.*cos((i2)/Vp2)).*F-(a+d*((cos(i1)/Vp1(lll))).*(cos(j2)/Vs2)).*H.*p.^2)./D;
    end
end

Upvotes: 0

Aero Engy
Aero Engy

Reputation: 3608

Try this. You 2 outer loops didn't do anything. You never used m or n so I killed those 2 loops. Also you just kept overwriting Rpp on every loop so your initialization of Rpp didn't do anything. I added an index var to assign the results to the equation to what I think is the correct part of Rpp.

Vp1=linspace(3000,3500,101);
Vp2=3850;
rho1=2390;
rho2=2510;
Vs1=linspace(1250,1750,101);
Vs2=2000;
i1=[10 25 40];
Rpp = zeros(length(Vp1)*length(Vs1),length (i1));
index = 1;
for l=1:length(Vp1)
    for k=1:length(Vs1)    

        p=sin(i1)/Vp1(l);
        i2=asin(p*Vp2);
        j1=asin(p*Vs1(k));
        j2=asin(p*Vs2);
        a=rho2*(1-2*Vs2^2*p.^2)-rho1*(1-2*Vs1(k).^2*p.^2);
        b=rho2*(1-2*Vs2^2*p.^2)+2*rho1*Vs1(k)^2*p.^2;
        c=rho1*(1-2*Vs1(k)^2*p.^2)+2*rho2*Vs2^2*p.^2;
        d=2*(rho2*Vs2^2-rho1*Vs1(k)^2);
        E=b.*cos(i1)./Vp1(l)+c.*cos(i2)/Vp2;
        F=b.*cos(j1)./Vs1(k)+c.*cos(j2)/Vs2;
        G=a-d*(cos(i1)/Vp1(l)).*(cos(j2)/Vs2);
        H=a-d*(cos(i2)/Vp2).*(cos(j1)/Vs1(k));
        D=E.*F+G.*H.*p.^2;
        Rpp(index,:)=((b.*(cos(i1)/Vp1(l))-c.*cos((i2)/Vp2)).*F-(a+d*((cos(i1)/Vp1(l))).*(cos(j2)/Vs2)).*H.*p.^2)./D;
        index = index+1;
    end
end

Results:

>> size(Rpp)

ans =

       10201           3

Upvotes: 1

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