[GiNaC-devel] Simplifying powers

Alexei Sheplyakov alexei.sheplyakov at gmail.com
Tue Jul 30 12:09:32 CEST 2013


Hi,

On Mon, Jul 29, 2013 at 10:41:01PM +0100, Vladimir V. Kisil wrote:

> Subject: [PATCH 3/3] Add an expansion law in power::expand(). The expansion
>  (x*p)^c -> x^c*p^c is done for a positive expression p
>  and a real exponent c. The corresponding check is added
>  to exam_powerlaws.
> 

> diff --git a/ginac/flags.h b/ginac/flags.h
> index 8f8f25d..f4f0f6b 100644
> --- a/ginac/flags.h
> +++ b/ginac/flags.h
> @@ -197,6 +197,9 @@ public:
>  		not_shareable   = 0x0010, ///< don't share instances of this object between different expressions unless explicitly asked to (used by ex::compare())
>  		has_indices	= 0x0020,
>  		has_no_indices	= 0x0040  // ! (has_indices || has_no_indices) means "don't know"
> +		is_positive	= 0x0080,
> +		is_negative	= 0x0100,
> +		purely_indefinite = 0x0200,  // If set in a mul, then it does not contains any terms with determined signs, used in power::expand()
>  	};
>  };

The `purely_idefinite' flag is redundant (that is !(is_positive || is_negative)
is equivalent to purely_indefinite). Also status_flags is quite a scarce
resource (there are only 32 of them). Could you please skip that flag?

Best regards,
	Alexei



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