Unless you expect exact result because all you are doing is copying, as soon as computation is involved you need to check either the relative error or the absolute error or both.
For instance, extracted [from my code](https://github.com/numforge/laser/blob/9fbb8d2a573d950573c7249e3a5d6cdd784a639e/laser/private/error_functions.nim#L6-L18): proc relative_error*[T: SomeFloat](y, y_true: T): T {.inline.} = ## Relative error, |y_true - y|/max(|y_true|, |y|) ## Normally the relative error is defined as |y_true - y| / |y_true|, ## but here max is used to make it symmetric and to prevent dividing by zero, ## guaranteed to return zero in the case when both values are zero. let denom = max(abs(y_true), abs(y)) if denom == 0.T: return 0.T result = abs(y_true - y) / denom proc absolute_error*[T: SomeFloat](y, y_true: T): T {.inline.} = ## Absolute error for a single value, |y_true - y| result = abs(y_true - y) Run In general you should prefer the relative_error especially with numbers not in the [-1, 1] range, but when the target is near 0, the relative change will get quite high due to the division and here you need to use the absolute error instead.
