# good afternoon everyone can anyone answer me this question ? i have an error in the matlab code

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No Freed el 23 de Nov. de 2019
Comentada: Walter Roberson el 24 de Nov. de 2019
here are some of the programs that I'm working on
sou_y = [5 10];
rec_y = [5 25 40];
d = [0.1000 0.0977 0.0908
0.1000 0.0977 0.0908];
pan_ray_total= [ 100.0000 101.9084 105.9481
100.1249 101.1187 104.4031];
t_obs = d;
vsem=zeros(length(sou_y),length(rec_y));
for i= 1 :length(sou_y)
for j= 1:length(rec_y)
vsem(i,j) = pan_ray_total(i,j)/t_obs(i,j);
end
end
v0_linier = sum (sum (vsem )) ./ n_ray ;
t_cal_linier = pan_ray_total ./ v0_linier;
dt_linier = t_obs - t_cal_linier;
for l = 1 :length(sou_y)
dt((length(rec_y)*(1-1 ))+1 :length(rec_y)* 1,1 ) =dt_linier(1,:);
end
G = [ 100.0000 0 0 ; 76.4853 25.4951 0; 45.4063 30.2709 0; 100.1249 0 0; 67.4125 33.7062 0; 34.8010 34.8010 34.8010];
G_linier = G ;
misfit = dt.^2;
We = (misfit).^-1;
m_linier = (inv(G_linier'*diag(We)*G_linier))*G_linier'*diag(We)*dt;
dv_linier = zeros(length(m_linier),l);
v_linier = zeros(length(m_linier),1);
for i = 1 :length(m_linier)
dv_linier (i) = (-1*m_linier(i)*v0_linier^2)/(1 + m_linier(i) * v0_linier);
v_linier(i) = v0_linier + dv_linier(i);
end
and i have problem like this
Error using *
Inner matrix dimensions must agree.
Error in te (line 21)
m_linier = (inv(G_linier'*diag(We)*G_linier))*G_linier'*diag(We)*dt;
how can i fix this?
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Walter Roberson el 23 de Nov. de 2019
No Freed el 23 de Nov. de 2019
i was input G value

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Walter Roberson el 23 de Nov. de 2019
I think you need
m_linier = (G_linier*diag(We)*G_linier')\G_linier*diag(We)*dt
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No Freed el 24 de Nov. de 2019
the formula that was given by walter is about resolved my program however i still found the error at matrix iteration like this
Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND =
5.516471e-18.
Thank you
Walter Roberson el 24 de Nov. de 2019
When you construct matrices based on 6 x 3 * 3 x 3 * 3 * 6, then the resulting matrix has rank no more than 3. It cannot possibly have an inverse.
You can proceed using pseudo-inverses, but it is not obvious that the result will have any meaning.
Question for you:
for l = 1 :length(sou_y)
So l is a loop control variable. After the loop, it will be left at the last value it was set to, so l = length(sou_y) is true after the for loop.
dv_linier = zeros(length(m_linier),l);
And there you set dv_linier to have l columns -- that is, to have length(sou_y) columns.
dv_linier (i) = (-1*m_linier(i)*v0_linier^2)/(1 + m_linier(i) * v0_linier);
but your syntax only assigns to dv_linier as if it is a vector. Unless you are doing linear indexing/
There are some valid cases to use linear indexing, but it is not obvious that this is any of those cases. My experiments suggest that it is not a place to use linear indexing to address multiple columns. I would suggest to you that perhaps when you define dv_linier that the number of columns should be 1 (the digit one) rather than l (lower-case L that got more or less accidentally left as length(sou_y))

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