Index in position 1 exceeds array bounds (must not exceed 1)?

I'm trying to run this function (Y is a 3 by 4 matrix)

function Y10 = RREF1 (Y)
Y1=Y(2,:)-(Y(2,1)/Y(1,1))*Y(1,:);
Y2=Y(3,:)-(Y(3,1)/Y(1,1))*Y(1,:);
Y3=Y2-(Y2(1,2)/Y1(1,2))*Y1;
Y4=Y3/Y3(1,3);
Y5=Y2-(Y2(1,3)/Y4(1,3))*Y4;
Y6=Y5/Y5(1,2);
Y7=Y(1,:)-(Y(1,3)/Y4(1,3))*Y4;
Y8=Y7-(Y7(1,2)/Y6(1,2))*Y6;
Y9=Y8/Y8(1,1);
Y10 = [Y9;Y6;Y4];
end

but I get this error each time i run RREF1 Y:

Index in position 1 exceeds array bounds. Index must not exceed 1.

Error in RREF1 (line 2)
Y1=Y(2,:)-(Y(2,1)/Y(1,1))*Y(1,:);

I don't understand which array is it talking about? I know Y does have more than one row or column

Answer 1

[Star Strider]

There must be something interfering with the function, since the code runs correctly here —

Y=[1 -3 5 -9; 2 -1 -3 19;3 1 4 -13]

Y = 3×4

1 -3 5 -9 2 -1 -3 19 3 1 4 -13

Yout = RREF1(Y)

Yout = 3×4

1 0 0 2 0 1 0 -3 0 0 1 -4

function Y10 = RREF1 (Y)
Y1=Y(2,:)-(Y(2,1)/Y(1,1))*Y(1,:);
Y2=Y(3,:)-(Y(3,1)/Y(1,1))*Y(1,:);
Y3=Y2-(Y2(1,2)/Y1(1,2))*Y1;
Y4=Y3/Y3(1,3);
Y5=Y2-(Y2(1,3)/Y4(1,3))*Y4;
Y6=Y5/Y5(1,2);
Y7=Y(1,:)-(Y(1,3)/Y4(1,3))*Y4;
Y8=Y7-(Y7(1,2)/Y6(1,2))*Y6;
Y9=Y8/Y8(1,1);
Y10 = [Y9;Y6;Y4];
end

See if there is another ‘RREF1’ function somewhere that could be running instead of this one.

.

Answer 2

[Cris LaPierre]

Apparently there is only one row in Y, and your code is trying to access a second row.

Y = 1:3

Y = 1×3

1 2 3

% Works
Y (1,1)

ans = 1

% Doesn't Work
Y(2,1)

Index in position 1 exceeds array bounds. Index must not exceed 1.

[ba sa]

but Y is 3 by 4

Y=[1 -3 5 -9; 2 -1 -3 19;3 1 4 -13]

I write this in the command window, and then run RREF1 Y and it gives me the error

[ba sa]

when I run the code in the command window it doesn't have a problem

Y1=Y(2,:)-(Y(2,1)/Y(1,1))*Y(1,:);
Y2=Y(3,:)-(Y(3,1)/Y(1,1))*Y(1,:);
Y3=Y2-(Y2(1,2)/Y1(1,2))*Y1;
Y4=Y3/Y3(1,3);
Y5=Y2-(Y2(1,3)/Y4(1,3))*Y4;
Y6=Y5/Y5(1,2);
Y7=Y(1,:)-(Y(1,3)/Y4(1,3))*Y4;
Y8=Y7-(Y7(1,2)/Y6(1,2))*Y6;
Y9=Y8/Y8(1,1);
Y10 = [Y9;Y6;Y4]

Y10 =

     1     0     0     2
     0     1     0    -3
     0     0     1    -4

but the function doesn't work

[Cris LaPierre]

You may have redefined Y somewhere in your code before it gets passed into RREF1. Your function is only getting a 1xn vector for Y, and not a 3x4 matrix.

How do you call RREF1 in your code?