I published a gist on how to get the gradient in any coordinate system,
given the backward transformation to rectangular coordinates.
I was also trying to write the code to get the divergence, but I ran into
problems with sympy's simplify( ) function.
https://gist.github.com/Upabjojr/34f75ce115
Hi Richard,
I do get your point that we don't have to make the same mistake with other
systems, but I do think there is a benefit for consistency, if they have a
purpose in doing that design. For most systems, sqrt() returns the
principal/positive square root, so there is only one unique value.
Hi Richard,
On Fri, Dec 5, 2014 at 4:48 PM, Richard Fateman wrote:
> You are heading into erroneous waters.
> It doesn't matter that 3>0. sqrt(9) has two values, +3 and -3.
> Just because some other systems make this mistake does not mean
> sympy should do this.
>
> If you want to say something
Something that I'm not sure about with representing functions as
multivalued is, how do you represent arbitrary Riemann surfaces.
Another question is computational. How do you compute the surfaces in
general (say even for a limited class of expressions, like algebraic
functions), and how do you ma
This is what I do for sqrt of real expression x (I want sqrt(abs(x))
without the abs() function in the result unless it is unavoidable)
def square_root_of_expr(expr):
if expr.is_number:
if expr > 0:
return(sqrt(expr))
else:
return(sqrt(-expr))
els
The Point class, for numerous functions, such as .evalf, returns a hard
coded Point class. This means that for a derived class, these functions
end up returning the original Point class not the derived class. I assume
there must be a way to code it differently so these functions return the
de
This is an issue in a lot of places in SymPy (see
https://github.com/sympy/sympy/issues/6751). The solution is to always
reference the class indirectly via self, and make use of super(),
isinstance(), and issubclass() (the exception is that the class does
have to be named explicitly in the argument
Well, upon closer examination, I find many uses of Point in point.py that I
don't know how to fix. I think my Python knowledge isn't quite there yet.
It appears many of the functions are intended be called off the class
rather than an instance, such as Point.is_collinear(p1, p2, p3, p4)
de
Am 06.12.2014 um 17:03 schrieb Yuxiang Wang:
Hi Richard,
I do get your point that we don't have to make the same mistake with other
systems, but I do think there is a benefit for consistency, if they have a
purpose in doing that design. For most systems, sqrt() returns the
principal/positive squ
On Sat, Dec 6, 2014 at 1:01 PM, Aaron Meurer wrote:
> Something that I'm not sure about with representing functions as
> multivalued is, how do you represent arbitrary Riemann surfaces.
>
> Another question is computational. How do you compute the surfaces in
> general (say even for a limited clas
This really should be a class method:
@classmethod
def is_collinear(cls, *points)
points = [cls(a) for a in points]
Note that this breaks backwards compatibility with the method being
called on an instance. Previously it would work, because the instance
would be the first element of points (w
Hi Joachim,
I was thinking of Mathematica and MATLAB Symbolic Toolbox, and both doing
symbolic math rather than numerical systems. My experience is limited to
these two though (that's the two my institution got a license for), so I'd
be open to hear on more example / counter-examples.
-Shawn
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