Assumptions system

[Paul Royik]

I know that variables can be made positive or negative.

But how do I make assumption that x>2?

If I have and expression like (x-2)^(1/3)+(x-5)^(1/3) (actually arbitrary expressions), how to make assumptions that all expressions under roots are positive, i.e. x-2>0, x-5>0?

[Aaron Meurer]

There is still limited support for this, but you can use refine(expr,
Q.positive(x - 2)). Actually, if all you want to do is simplify all
roots in an expression you can use powdenest() and powsimp() with the
force=True flag.

Aaron Meurer

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[Paul Royik]

Thank you.

On Friday, January 17, 2020 at 10:34:39 PM UTC+2, Aaron Meurer wrote:

There is still limited support for this, but you can use refine(expr,
Q.positive(x - 2)). Actually, if all you want to do is simplify all
roots in an expression you can use powdenest() and powsimp() with the
force=True flag.

Aaron Meurer

On Fri, Jan 17, 2020 at 12:26 PM Paul Royik <distan...@gmail.com> wrote:
>
> I know that variables can be made positive or negative.
>
> But how do I make assumption that x>2?
>
> If I have and expression like (x-2)^(1/3)+(x-5)^(1/3) (actually arbitrary expressions), how to make assumptions that all expressions under roots are positive, i.e. x-2>0, x-5>0?
>
> --
> You received this message because you are subscribed to the Google Groups "sympy" group.

> To unsubscribe from this group and stop receiving emails from it, send an email to sy...@googlegroups.com.