Replacing elements in matrix with relational operations

I am given a problem where I am given a matrix and I am suppose to change the values of the matrix depending on if a certain element of the matrix is greater than or less than a number. If it is greater than the variable n1 I am suppose to change the element to c1 and if is less than n1 I am suppose to change it to c2. I am to use only relational operations, I cannot use for, if, while or any implicit functions. How can I do this? This is what I have so far m3 is the matrix I am given

m4 = ((m3>n1)*c1)
m5 = ((m3<=n1)*c2)

Answer 1

[David Sanchez]

M=randi(10,3);
n1 = 5;
c1 = 4;
c2 = 3;

M1 = M<5;
D1 = c1*M1;
M2 = M>=5;
D2 = c2*M2;

new_M = D1 + D2;

% In a single line
new_M = c1*(M<5) + c2*(M>=5);

Adapt the values of n1, c1 and c4 to yours needs.

[David Sanchez]

I meant to use n1 instead of its value:

% In a single line
new_M = c1*(M<n1) + c2*(M>=n1);

[Walter Roberson]

Addition is an implicit function in MATLAB: the method @double/plus will be called in this situation. Multiplication is also a function; I think @double/mtimes would be called for your code suggestion. Note that .* would be better than * in your code

Your code suggestion does not leave unchanged the parts of M that do not satisfy the conditions.

Answer 2

[Walter Roberson]

The task cannot be accomplished without using at least one implicit function other than the relational operators.

http://www.mathworks.co.uk/matlabcentral/answers/38787-what-can-be-programmed-without-any-built-in-functions