- `Y = double (X)`

Convert `X` to double-precision floating-point form.

For numeric input, return values represented as double precision numbers. For
logical and character input, return the corresponding numeric values in double
precision.

See also: `single`, `char`, `logical`.

### References

- https://www.mathworks.com/help/matlab/ref/double.html
- https://octave.sourceforge.io/octave/function/double.html