MATLAB: In an assignment A(I) = B, the number of elements in B and I must be the same, error.

loop

x =

X =

q=6;

for i=1:q

   dk(i)=x-X(i)

end

%it gives me the error.

%in this statement, I wanna create this situation,

dk(1)=x-X(1)

dk(2)=x-X(2)

dk(3)=x-X(3)

dk(4)=x-X(4)

dk(5)=x-X(5)

dk(6)=x-X(6)

What kind of loop I need to create these "dk".

Best Answer

x - vector -> dk1 = x-X(1), here dk1 - vector with length of x

in your case dk - matrix with size 6 x 5:

dk = zeros(numel(X),numel(x));
for jj = 1:numel(X)
    dk(jj,:) = x - X(jj);
end

dk = bsxfun(@minus,x(:)',X(:));

Related Solutions

MATLAB: Matrix dimensions must agree.

>> whos
  Name      Size            Bytes  Class     Attributes
  a         1x1                 8  double              
  b         1x8                64  double              
  b1        1x7                56  double              
  b2        1x6                48  double              
  b3        1x5                40  double              
  b4        1x4                32  double              
  b5        1x3                24  double              
  b6        1x2                16  double              
  b7        1x1                 8  double              
  dx        1x1                 8  double              
  x         1x9                72  double              
  yy        1x9                72  double

The result of diff is shorter, being always the difference between elements.

sometimes;

  something = [0,diff(somethingElse)]

can be useful.

MATLAB: Is there a faster way than repeating this calculation manually

 function F = TEST6lijn300(x, p)
    F = [(x(1)^2 + x(2)^2 - p(1));
     ((1447.5-x(3))^2 + (876.3-x(4))^2-p(2));
     ((-72.4-x(5))^2 + (1723.1-x(6))^2-p(3));
    (x(5)^2 - 2*(x(5)*x(1)) + x(1)^2 + x(6)^2 - 2*(x(6)*x(2)) + x(2)^2 - 20449);
    (x(3)^2 - 2*(x(3)*x(1)) + x(1)^2 + x(4)^2 - 2*(x(4)*x(2)) + x(2)^2 - 20449);
    (x(3)^2 - 2*(x(3)*x(5)) + x(5)^2 + x(4)^2 - 2*(x(4)*x(6)) + x(6)^2 - 20449)];
 end

The call would be

 ...
 p = [753233.1, 966977.2, 957129.6] ;
 [x,fval] = fsolve(@(x)TEST6lijn300(x,p),x0,options) ;

EDIT2: if all your sets of p values are in an Excel file, you can do the following (that you could make more concise by eliminating temporary variables):

 x0 = ... 
 options = ...
 filename = 'myFile.xlsx' ;
 sheet = 'mySheet' ;
 P = xlsread(filename, sheet) ;          % Assuming that there is no numerical
                                         % header in your spreadsheet.
 n = size(P, 1) ;                        % Number of rows (sets of p values).
 X = zeros(n, length(x0)) ;              % Prealloc for storing x's.
 for ii = 1 : n
    fh = @(x) TEST6lijn300(x, P(ii,:)) ; % See note below.
    X(ii,:) = fsolve(fh, x0, options) ;
 end

Note: fh is a function handle on an anonymous function that takes 1 input parameter, x, and calls your function TEST6lijn300 with the two arguments that it requires, here x and ii-th row of P that is the ii-th set of p values. Jan's comment refers to a post explaining that using an anonymous function is the proper way to manage this type of situations where you have to match interfaces between your function and some solver requirements.

Cedric

Best Answer

Related Solutions

MATLAB: Matrix dimensions must agree.

MATLAB: Is there a faster way than repeating this calculation manually

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