Subscript indices must either be real positive integers or logicals?

When I input option 2, then input the matrix, everything goes fine until the transpose function. It reads an error message titled, "Subscript indices must either be real positive integers or logicals." How do I get rid of this?

Marix = [1 2 1 ; 0 2 0 ; 2 1 1]

Thanks for the help

clc;
fprintf('Matrix operations (0 to end program):\n');
fprintf('1 create a matrix\n');
fprintf('2 operation on 1 matrix\n');
fprintf('3 operation on 2 matrices\n');
i = input('Enter option: ');
while i ~= 0
    if i == 1
        fprintf('Create matrices\n')
        fprintf('Create a matrix of ones, zeroes, random numbers, identity\n')
        rows = input('Enter number of rows:');
        columns = input('Enter number of columns:');
        ones_matrix = ones(rows,columns)
        zeros_matrix = zeros(rows,columns)
        random_matrix = rand(rows,columns)
        identity_matrix = eye(rows,columns)
    end
    if i == 2
        fprintf('Operations on one matrix\n')
        matrix_1 = input('Enter matrix 1: ');
        if abs(det(matrix_1)) <= 1e-15
            fprintf('Singular matrix, no determinant or inverse\n')
        else
            fprintf('Determinant, inverse\n')
            determinant = det(matrix_1)
            inverse = inv(matrix_1)
        end
        fprintf('Multiply matrix1 by a scalar\n');
        scalar = input('Enter scalar:');
        scalar_mult = matrix_1 * scalar
        fprintf('Transpose matrix 1\n');
        transpose = transpose(matrix_1)
    end
    if i == 3
        fprintf('operations on two matrices\n')
        matrix_1 = input('Enter matrix 1: ');
        matrix_2 = input('Enter matrix 2: ');
        fprintf('add, element by element multiplication\n');
        [a b] = size(matrix_1);
        [c d] = size(matrix_2);
        if a ~= c
            fprintf('Matrices do not have same dimensions cannot add, or do element by element multiplication');
        else
            fprintf('Add matrix1 and matrix2\n');
            matrix_add = matrix_1 + matrix_2
            fprintf('Element by element multiplication\n');
            ele_mult = matrix_1 .* matrix_2
        end
        if b ~= c
            fprintf('Columns of matrix1 ~= rows of matrix2, cannot do matrix multiplication\n');
        else
            matrix_mult = matrix_1 * matrix_2
        end
    end
    if i>3 || i<0
        fprintf('Option entered: %d is invalid\n',i)
    end

      fprintf('Matrix operations (0 to end program):\n');
      fprintf('1 create a matrix\n');
      fprintf('2 operation on 1 matrix\n');
      fprintf('3 operation on 2 matrices\n');
      i = input('Enter option: ');
  end

Answer 1

[Star Strider]

You are ‘overshadowing’ the transpose function here:

transpose = transpose(matrix_1);

If you name a variable the same as a function, the next time MATLAB encounters the name, it will assume you are referring to the variable, not the function.

Solution: Rename the variable so there is no conflict with the function name.

[Zach Koenig]

No matter what I name the variable I run into this problem.

[Star Strider]

I get the error with this code:

matrix_1 = [2 1; 3 4]*0.1
transpose = transpose(matrix_1)
transpose = transpose(matrix_1)             % Same ‘Subscript indices must either be real positive integers or logicals.’ Error Here

but not with this:

matrix_1 = [2 1; 3 4]*0.1
transpose = transpose(matrix_1)
clear transpose                             % Clear The ‘transpose’ Variable (Function Unaffected)
transpose = transpose(matrix_1)             % No Error Here

also:

matrix_1 = [2 1; 3 4]*0.1
trps = transpose(matrix_1)                  % No Error Here
trps = transpose(matrix_1)                  % No Error Here
trps = transpose(matrix_1)                  % No Error Here

This leads me to believe my ‘overshadowing’ hypothesis is correct.

Answer 2

[Image Analyst]

See the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_fix_the_error_.22Subscript_indices_must_either_be_real_positive_integers_or_logicals..22.3F