Re: Symbolica package warning: Using rat() heuristics for double-precision input (is this what you wanted?)

[Colin Macdonald]

On 17/02/17 09:17, Mike Miller wrote:
> No, there is something magic about the double value returned by pi.
>
> The function that converts numeric values has special code to test
> whether a given double value is exactly pi (to the extent of double
> precision), and replaces that with the string value "pi" for SymPy to
> evaluate.

Yes: so using vpa('pi') is probably a good habit.

Basically anytime you are passing a double into "sym" or "vpa", you 
should think carefully about what you are doing.

I considered having "vpa" give the "rats" warning or something similar 
so "vpa(pi/2)" would give a warning to help folks learn this.  But maybe 
its a valid thing to do, unlike "sym(1.23)" which almost certainly wrong.

Colin