Matrix manipulation by function

Dear all, For a given matrix (square) i need to eliminate some elements (some rows and columns)

A = 
    35     6    19
     3     7    23
    31     2    27

I need only the second (not the first and the third) row and column : the eliminated are stocked in a vector

B = (1 3)

So : some function (A, B) :::> the result C = 7

function (A, B) = C

[KSSV]

iwant = A(2,2)

wont it solve the purpose?

[Lila wagou]

Dear KSSV, i need a function for lot of use

A1 = 
      35     6    19
       3     7    23
      31     2    27
and
B1 = (1 3)
C1 = 7
or
A2 = 
      35     6    19  11
       3     7    23  44
      31     2    27  55
      31     2    27  55
and
B2 = (2 3)
C2 = 
      35     11
      31     55

Answer 1

[Andrei Bobrov]

ii = num2cell([1;1]*setdiff(1:length(A),B(:)'),2);
out = A(ii{:});

[Lila wagou]

Dear Andrei; please why 2 in ,B(:)'),2); thanks

[Andrei Bobrov]

Please read about num2cell, it's 'dim'.

[Lila wagou]

Dear Andrei; thanks the explication, is it possible to get only the the first and the third (not the second) rows and columns : the wanted are stocked in a B vector

A = 
        35     6    19
         3     7    23
        31     2    27
B = (1 3)
C = function (A, B)
C = 
          35     19
          31     27

[Andrei Bobrov]

   C = A(B,B)

[Lila wagou]

Dear Andrei; Thank you a lot for your valued assistance.

[judy abbott]

Hy Lila, Hy Andrei Bobrov, i have a same need but for a vector, for a V_old vector i want to insert the V_ins vector in the order of V_ord vector (the value of 10 replace the 1 element of V_old, the value of 20 replace the 3 element of V_old):

V_old = zeros(1,3);
V_ins = [10 20];
V_ord = [1 3];

I want to write a function

V_new = MyFunction(V_old, V_ins, V_ord)

to get V_new = 10 0 20

Thank

[Andrei Bobrov]

V_new = V_old;
V_new(V_ord) = V_ins;

[Lila wagou]

Dear Andrei; please how to trait a vector (eliminate the elements stocked in a vector by order)

A = [10 52 33]
B = [3]
ii = num2cell([1]*setdiff(1:length(A),B(:)'),1);
out = A(ii{:});

i get out = 52 so i must get out = 10 52

Answer 2

[Fangjun Jiang]

C=A;
C(B,:)=[];
C(:,B)=[]

[Andrei Bobrov]

Hi Fangjun!

[Jan]

Yes, hi Fangjun!

[Fangjun Jiang]

Hello, friends!