pub fn col_mut(&mut self, j: usize) -> &mut [f64] {
        let index = j * self.nrows;

        &mut self.data[index..index + self.nrows]
    }
/// Get a "column" of the array as a slice.
Get a "column" of the array as a slice.
Get a " column " of the array as a slice .
pub fn col_mut(&mut self, j: usize) -> &mut [f64] {
        let index = j * self.nrows;
        &mut self.data[index..index + self.nrows]
    }
pub fn col_mut ( & mut self , j : usize ) -> & mut [ f64 ] { let index = j * self . nrows ; & mut self . data [ index .. index + self . nrows ] }
Get a "column" of the array as a slice.
Get a " column " of the array as a slice .
&mut self
j
usize