Re: [sympy] bug in lowergamma derivative ?

2013-09-26 Thread James Fiedler
Thanks. I think I got it. I just submitted the pull request. I think there already was a test for the derivative with respect to first argument, but it also had the wrong sign. James On Thursday, September 26, 2013 7:30:29 PM UTC-5, Aaron Meurer wrote: > > No problems. We have a guide written u

Re: [sympy] evalf keeping precision

2013-09-26 Thread Aaron Meurer
I guess the problem is that y*1.0 is translated into y*Float(1.0), and Float(1.0) is the same as Float(1.0, 15), and it goes with the higher precision. I don't know why it does this. It seems to me that it should go with the smallest number of digits, not the largest, but maybe there's a good reaso

Re: [sympy] Re: Pattern matching

2013-09-26 Thread Aaron Meurer
My idea was to put assumptions on Wild expressions. I guess using the new assumptions system, the assumptions do not need to be, nor should they be, actually tied to the symbols. This will also make it easy to add assumptions about general expressions, not just Wilds (and make it easier to do the s

Re: [sympy] bug in lowergamma derivative ?

2013-09-26 Thread Aaron Meurer
No problems. We have a guide written up at https://github.com/sympy/sympy/wiki/development-workflow. Or just ask here or on our IRC channel if you need help. Aaron Meurer On Thu, Sep 26, 2013 at 3:13 PM, James Fiedler wrote: > Hi, > > Yeah, I'm willing to do that. I'm actually trying to learn Gi

Re: [sympy] Re: Handling derivatives while evaluating the Inverse Laplace Transform of Functions

2013-09-26 Thread Aaron Meurer
The solution to this is to call apart on the arguments. For instance In [9]: apart(2/(s**2*(s**2 + 1))) Out[9]: 2 2 - ── + ── 22 s + 1 s In [10]: inverse_laplace_transform(-2/(s**2 + 1), s, t) Out[10]: -2⋅sin(t)⋅Heaviside(t) In [11]: inverse_laplace_transform(2/s**2,

[sympy] Re: Handling derivatives while evaluating the Inverse Laplace Transform of Functions

2013-09-26 Thread Harsh Gupta
Hi, Sympy is directly using inverse Millen formula Integral(exp(s*t)*F, (s, c - I*oo, c + I*oo)) to evaluate the inverse_laplace_transform function. But it is not working well with some functions which can be easily evaluated by hand. For example 1. A NotImplementedError is raised when I tr

Re: [sympy] bug in lowergamma derivative ?

2013-09-26 Thread James Fiedler
Hi, Yeah, I'm willing to do that. I'm actually trying to learn Git now, so this would be good practice. Of course, that also means it might take me a minute to figure out how to do this. James On Thursday, September 26, 2013 3:32:45 PM UTC-5, Tom Bachmann wrote: > > Hi, > > good catch. Thank

Re: [sympy] Re: Pattern matching

2013-09-26 Thread F. B.
On Thursday, September 26, 2013 8:39:28 PM UTC+2, Ondřej Čertík wrote: > > On Thu, Sep 26, 2013 at 11:45 AM, F. B. > > wrote: > > What's your idea to include assumptions in pattern matching? > > > > I have some hypothetical uses: > > > > a = Wild('a', assumptions=[Q.is_positive]) > > a = W

Re: [sympy] bug in lowergamma derivative ?

2013-09-26 Thread Tom Bachmann
Hi, good catch. Thanks for reporting this. I wrote the code, made a small misstake, and overlooked adding a test which would easily have uncovered this. Here is a one-line fix: diff --git a/sympy/functions/special/gamma_functions.py b/sympy/functions/special/gamma_functions.py index 86e292

[sympy] evalf keeping precision

2013-09-26 Thread Duane Nykamp
Is this intended behavior of evalf or N? It evaluates to the precision specified, but future calculations involving the number return to the previous precision. In [56]: x=Float("1.234567") In [57]: y=N(x,2) In [58]: y Out[58]: 1.2 In [59]: y*1.0 Out[59]: 1.234375 I was thinking it

[sympy] bug in lowergamma derivative ?

2013-09-26 Thread James Fiedler
Hello, The example below demonstrates what looks to me like a bug in the lowergamma derivative. The example shows that the derivative is very different from approximations to it. Is this a bug, or have I just messed up something? In [1]: import sympy > > In [2]: sympy.__version__ > Out[2]: '

Re: [sympy] Re: Pattern matching

2013-09-26 Thread Ondřej Čertík
On Thu, Sep 26, 2013 at 11:45 AM, F. B. wrote: > What's your idea to include assumptions in pattern matching? > > I have some hypothetical uses: > > a = Wild('a', assumptions=[Q.is_positive]) > a = Wild('a'); a & Q.is_positive(a) > expr.match(expr2, assumptions= ... ) What difference would it mak

[sympy] Re: Pattern matching

2013-09-26 Thread F. B.
What's your idea to include assumptions in pattern matching? I have some hypothetical uses: 1. a = Wild('a', assumptions=[Q.is_positive]) 2. a = Wild('a'); a & Q.is_positive(a) 3. expr.match(expr2, assumptions= ... ) Any better ideas? -- You received this message because you are subs

[sympy] Re: Handling derivatives while evaluating the Inverse Laplace Transform of Functions

2013-09-26 Thread Saurabh Jha
Hi Harsh, Please have a look at our Development Workflow page[1] to get started. If you have already gone through this, submit a pull request so that we can review it and check it in. Start small and just push your preliminary ideas first so that we can discuss and refine it. -Saurabh [1] htt

[sympy] Handling derivatives while evaluating the Inverse Laplace Transform of Functions

2013-09-26 Thread Harsh Gupta
Hello, I was going through the sympy source-code to find out how to computationally calculate the Inverse Laplace Transform of Functions. While reading the code I found a TODO ``` # TODO handle derivatives etc ``` in symp.integrals.transforms line 152 I would like to solve this. So, can y