On 1/25/11 11:38 AM, kcrisman wrote:
On Jan 25, 12:27 pm, Jason Grout<jason-s...@creativetrax.com> wrote:
On 1/25/11 11:17 AM, kcrisman wrote:
If f is a function explicitly of one variable (e.g., f(x)=x^3+1), then
it makes sense to use this variable as a default for differentiation or
integration. However, if we are dealing with just a symbolic expression
(e.g., f=x^3+1), then a default makes less sense to me.
Correct, that was the rationale. I disagree, if there is only one
variable in the expression.
(to recap discussion from before for those that weren't on the list at
that time...)
I agree with Robert on this one. If you have symbolic expressions:
var('x,y')
a=x+y
b=-y
then it seems you would have integrate(a+b) behave differently than
integrate(a). That's why it makes less sense to me; to avoid confusion,
the user should specify intent somewhere. In the f(x)=a+b case, the
user is specifying that a+b is only a function of x, so the integral can
use a default variable without confusion.
Wait, now *I'm* confused. Are you suggesting that
integrate(b)
should or should not have a deprecation/require integrate(b,y)? In
particular, I'm not sure what agreeing with Robert means :)
Let me be more clear. I think that:
integrate(a) and diff(a) should be deprecated/not supported
integrate(b) and diff(b) be deprecated/not supported
integrate(a+b) and diff(a+b) be deprecated/not supported
(each of these should require a explicit variable specified)
I think this is similar to how we insist that students write the
variable of integration after the "d" in an integral.
However, in the case of callable functions with variables specified, I
suppose it would be a nice shortcut to use the explicit intent the user
expressed when creating the function to have a default variable for
integration and differentiation.
Jason
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