how to creat if loop?

function [B]=BusData
% ---------------------------------data input------------------------------
%bus number| Bus type | voltage schedule | Pgen | Pload | Qload
syms Swing
syms Gen
syms Load
syms Pg
syms Pl
syms Ql
B =[1 Swing 1.05 Pg Pl Ql 
    2 Gen 1.05 0.5 0 0
    3 Gen 1.07 0.6 0 0
    4 Load 0 0 0.7 0.7
    5 Load 0 0 0.7 0.7
    6 Load 0 0 0.7 0.7]
end
%-----------------------------------------------------program strat here-------------------------------------------------------------
%Bus parameters:
bn = B(:,1);
bt = B(:,2);
vs = B(:,3);
Pgen  = B(:,4);
Pload = B(:,5);
Qload = B(:,6);

mat %mat is 6*6 matrix
E=inv(mat)
%[P1;P2;...;Pn-1]=C
%[q1;1q2;...;qn-1]=D
C=E*D
syms Swing
for i=1:bn
if bt==Swing
    E(i,:) = [];
    E(:,i) = [];
end
end
disp(E)

and i want to do this for C & D and by the way n depends on which row of B is Swing(so if bn=2 is Swing then delete second row and second column if nb=1 is swing delete first row and column of mtarix E if... ) but i want this code to be general and i have tried many things but still confused and not getting my ans...

Answer 1

[Walter Roberson]

Your function does not expect any input parameters.

Your function does not define a variable named mat . Therefore in order for the line

mat %mat is 6*6 matrix

to not be an error, then mat would have to be a function that you are invoking.

Then you do

E=inv(mat)

which is not inconsistent with the possibility that mat is a function... as long as the function returns a square matrix.

C=E*D

You have not defined any variable named D so in order for that line to be valid, D must be a function that you are invoking.

if bt==Swing

You have not defined any variable named bt so in order for that line to be valid, bt must be a function that you are invoking

    mat(n,:) = [];
    mat(:,n) = []

You have not defined any variable named n so in order for that line to be valid, n must be a function that you are invoking.

However... we have established that mat must be a function. It is potentially valid to invoke a function with two parameters, one of which is : . However, it is never valid for the output of a function to be the destination for assignment or deletion using [] .

[arian hoseini]

you are right ...thats because i didnt write the entire code here so

E = [
    -0.4296    0.2606   -0.0183    0.2978   -0.3535    0.0347
    0.2606   -0.2000   -0.0034   -0.0973    0.3342   -0.0480
    -0.0183   -0.0034   -0.0359   -0.0401    0.0732    0.0791
    0.2978   -0.0973   -0.0401   -0.1889    0.3016   -0.0705
    -0.3535    0.3342    0.0732    0.3016   -0.8023    0.1629
    0.0347   -0.0480    0.0791   -0.0705    0.1629   -0.0564];

just tell me what should i do with E

and forget that C=E*D

[Walter Roberson]

driver()

B = 

Unrecognized function or variable 'mat'.

Error in solution>driver (line 24)
mat() %mat is 6*6 matrix

function driver
    syms Swing
    syms Gen
    syms Load
    syms Pg
    syms Pl
    syms Ql
    B =[1 Swing 1.05 Pg Pl Ql 
        2 Gen 1.05 0.5 0 0
        3 Gen 1.07 0.6 0 0
        4 Load 0 0 0.7 0.7
        5 Load 0 0 0.7 0.7
        6 Load 0 0 0.7 0.7]
    %-----------------------------------------------------program strat here-------------------------------------------------------------
    %Bus parameters:
    bn = B(:,1);
    bt = B(:,2);
    vs = B(:,3);
    Pgen  = B(:,4);
    Pload = B(:,5);
    Qload = B(:,6);
    
    mat() %mat is 6*6 matrix
    E = inv(mat)

    E = [
        -0.4296    0.2606   -0.0183    0.2978   -0.3535    0.0347
        0.2606   -0.2000   -0.0034   -0.0973    0.3342   -0.0480
        -0.0183   -0.0034   -0.0359   -0.0401    0.0732    0.0791
        0.2978   -0.0973   -0.0401   -0.1889    0.3016   -0.0705
        -0.3535    0.3342    0.0732    0.3016   -0.8023    0.1629
        0.0347   -0.0480    0.0791   -0.0705    0.1629   -0.0564];
    
    n = find(ismember(bt, Swing));
    mat(n,:) = []

Using 'mat' as the name of a variable and the name of a nested function in the same scope is not supported.

    mat(:,n) = []
    
    function MAT = mat()
      MAT = magic(6);
    end
end