how to write a correlation coefficient code with only the use of SUM function.

how to write a correlation coefficient code with only the use of SUM function.

YES, you can not just use

corrcoef(x,y)
mean(x) mean(y)
std(x) std(y)

to write this code.

literally writing a function to find correlation coefficient with SUM as the only intrinsic function

Answer 1

[Walter Roberson]

That is not possible. The Pearson Correlation Coefficient cannot be calculated without multiplications or divisions.

https://en.wikipedia.org/wiki/Pearson_correlation_coefficient#For_a_sample

Notice the use of . That is defined as which is something that cannot be calculated without at least one division.

[alexander fastiggi]

I never said you can't multiply or divide.

[Walter Roberson]

Yes you did!! I quote,

with only the use of SUM function

In MATLAB, multiplication and division are functions. The .* operator is formally known as times and the ./ operator is formally known as rdivide . .* and ./ are "syntax sugar" .

A .* B

is exactly the same as times(A, B) -- a function call.

In MATLAB, neverly everything is a function. Subscripting is a function. Assignment is the function whose formal name is subsasgn() .

These are the only things in MATLAB that are not functions:

>> iskeyword
ans =
  20×1 cell array
    {'break'     }
    {'case'      }
    {'catch'     }
    {'classdef'  }
    {'continue'  }
    {'else'      }
    {'elseif'    }
    {'end'       }
    {'for'       }
    {'function'  }
    {'global'    }
    {'if'        }
    {'otherwise' }
    {'parfor'    }
    {'persistent'}
    {'return'    }
    {'spmd'      }
    {'switch'    }
    {'try'       }
    {'while'     }