Hi Michael,
On 2019-03-11, Michael Beeson wrote:
> I tried various simplification functions.I suppose I could start over,
> not using "symbolic expressions" but
> declaring K to be a suitable field or ring, maybe a quadratic extension of
> the field of rational functions in a.
> That is
Le lundi 11 mars 2019 19:05:04 UTC+1, Michael Beeson a écrit :
>
> I appreciate Eric's post, and I do use subs sometimes, but it makes me
> nervous since
> it will happily substitute any old thing you tell it to, even an
> incorrect thing. So, if your idea
> is to check a computation, it i
On Monday, March 11, 2019 at 11:05:04 AM UTC-7, Michael Beeson wrote:
>
> I appreciate Eric's post, and I do use subs sometimes, but it makes me
> nervous since
> it will happily substitute any old thing you tell it to, even an
> incorrect thing. So, if your idea
> is to check a computatio
I appreciate Eric's post, and I do use subs sometimes, but it makes me
nervous since
it will happily substitute any old thing you tell it to, even an incorrect
thing. So, if your idea
is to check a computation, it is a dangerous thing. True, if you put only
correct equations in,
you'll
What about something like
sage: var('p,q,r,a')
(p, q, r, a)
sage: b = sqrt(1-a^2)
sage: eq = (p*a+r*b+q)^2
sage: eq = eq.expand(); eq
a^2*p^2 - a^2*r^2 + 2*sqrt(-a^2 + 1)*a*p*r + 2*a*p*q + 2*sqrt(-a^2 + 1)*q*r
+ q^2 + r^2
sage: b = var('b')
sage: eq.subs({sqrt(1-a^2): b})
a^2*p^2 + 2*a*b*p*r - a^
