Re: [Numpy-discussion] Calculating tan inverse

2006-11-08 Thread Nadav Horesh








There is arctan function
in numpy, and in math (atan, atan2)

 

  Nadav.

 









From:
[EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of amit soni
Sent: Wednesday, November 08, 2006
19:36
To:
numpy-discussion@lists.sourceforge.net
Subject: [Numpy-discussion]
Calculating tan inverse



 

how can I calculate arctan of a number in python?
thanks
Amit

 








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Re: [Numpy-discussion] matrix multiplication (newbie question)

2006-11-08 Thread Nadav Horesh








Make A,B,… matrices
instead of arrays, so instead

A = array((…..))

Write

A = matrix((….))

 

Assuming you had

From numpy import *

 

  Nadav

 









From:
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[mailto:[EMAIL PROTECTED] On Behalf Of izak marais
Sent: Wednesday, November 08, 2006
15:54
To:
numpy-discussion@lists.sourceforge.net
Subject: [Numpy-discussion] matrix
multiplication (newbie question)



 

Hi

Sorry if this is an obvious question, but what is the easiest way to multiply
matrices in numpy? Suppose I want to do A=B*C*D. The ' * ' operator apparently
does element wise multiplication, as does the 'multiply' ufunc. All I could
find was the numeric function 'matrix_multiply, but this only takes two
arguments.

Thanks in advance!
Izak

 








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Re: [Numpy-discussion] Model and experiment fitting.

2006-10-21 Thread Nadav Horesh

1. If at least one of your data sets to be interpulated is on a grid, you can 
use numpy.ndimage.map function for fast interpolation for 2d (in fact for any 
dimensional) dataset.

2. Isn't there an analytic expression to average the expectration values of SH 
over all possible orientations between B and the crystal axis? My experience 
shows that some analytic work can save 99% of simulation time.

  Nadav

-Original Message-
From:   [EMAIL PROTECTED] on behalf of Sebastian Zurek
Sent:   Sat 21-Oct-06 15:41
To: numpy-discussion@lists.sourceforge.net
Cc: 
Subject:Re: [Numpy-discussion] Model and experiment fitting.

Robert Kern napisal(a):

> Your description is a bit vague. 

Possibly by my weak English... I'll try to make myself clearer now.

Do you mean that you have some model function f
> that maps X values to Y values?
> 
>f(x) -> y
> 

My model is quantum energy operator - spin hamiltonian (SH) with some
additional assumption about so called 'line shape', 'line widths',etc.

   It describes various electron interactions, visible in electron 
paramagnetic resonance (EPR, ESR) experiment. The simplest SH can
be written in a form:
H = m B g S   (1)
where m is a constant (bohr magneton), B is magnetic field (my 
x-variable), g is so called 'zeeman matrix' and S is total spin angular
momentum operator.

Summing it all together: the simple model is parametrized by:
  - line shape,
  - line width,
  - zeeman matrix (3x3 diagonal matrix - the spatial dependence),
  - total spin S.

After SH (1) diagonalization one can obtain so called 'resonance fields' 
and  'resonance intensities'. After a convolution with appropriate  line 
shape function which is parametrized by the line width one can finally
get the simulated EPR spectrum (simDat=[[X1,...,Xn],[Y1,...,Yn]]).
This  is a roughly, schematic description, appropriate to EPR spectra of
monocrystals.

In my situation the problem is more sophisticated - I have 
polycrystaline (powders) data, and to obtain a simulated EPR powder 
spectrum I need to sum up the EPR spectra of monocrystals that come from 
many possible spatial orientations, and the resultant spectrum is an 
envelope of all the monocrystals spectra.

There's no simple model function that maps X -> Y.


> If that is the case, is there some reason that you cannot run your simulation 
> using the same X points as your experimental data?
> 

I can only demand a X range and number of X values within the range, 
there's no possibility to find the Y(X) for a specified X. These 
limitations on one hand come from  the external program I'm using to 
simulate the EPR spectra, on the other are a result of spatial averaging 
of EPR data for powders, where a lot of interpolations are involved.


> OTOH, is there some other independent variable (say Z) that *is* common 
> between 
> your experimental and simulated data?
> 
>f(z) -> (x, y)
> 

This is probably the situation I'm in. These other variables are my 
model parameters, namely: line shape-width, zeeman matrix... and they're
commen between the experiment and the simulation.


To make it clear.

I've already solved the problem by a simple linear interpolation of 
simulated points within the narrow neighborhood of experimental data 
point. The simulation points are uniformly distributed along the 
X-range, with a density I'm able to tune. It all works quite well but 
I'm founding it as a 'brute-force' method and I wonder, if there's any 
more sophisticated and maybe already incorporated into any Python module 
method?

Anyway, it looks like it's impossible to compare two discrete 2D data 
sets without any interpolations included... :]


A. M. Archibald has proposed spline fitting, which I'll try. I'll also 
look at the Numerical Recipes discussion he has proposed.


Sebastian


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Re: [Numpy-discussion] tensor product

2006-10-07 Thread Nadav Horesh

There is a "tensortdot" function in numpy1.0rc1

  Nadav

-Original Message-
From:   [EMAIL PROTECTED] on behalf of Charles R Harris
Sent:   Sun 08-Oct-06 06:54
To: numpy-discussion@lists.sourceforge.net
Cc: 
Subject:[Numpy-discussion] tensor product

Hmmm,

I notice that there is no longer a tensor product. As it was the only one of
the outer, kron bunch that I really wanted, l miss it. In fact, I always
thought outer should act like the tensor product for the other binary
operators too. Anyway, mind if I put it back?

Chuck



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Re: [Numpy-discussion] tensor dot ?

2006-08-26 Thread Nadav Horesh
I once wrote a function "tensormultiply" which is a part of numarray 
(undocumented). You can borrow it from there.

  Nadav


-Original Message-
From:   [EMAIL PROTECTED] on behalf of Simon Burton
Sent:   Fri 25-Aug-06 14:42
To: numpy-discussion@lists.sourceforge.net
Cc: 
Subject:[Numpy-discussion] tensor dot ?


>>> numpy.dot.__doc__
matrixproduct(a,b)
Returns the dot product of a and b for arrays of floating point types.
Like the generic numpy equivalent the product sum is over
the last dimension of a and the second-to-last dimension of b.
NB: The first argument is not conjugated.

Does numpy support summing over arbitrary dimensions,
as in tensor calculus ?

I could cook up something that uses transpose and dot, but it's
reasonably tricky i think :)

Simon.

-- 
Simon Burton, B.Sc.
Licensed PO Box 8066
ANU Canberra 2601
Australia
Ph. 61 02 6249 6940
http://arrowtheory.com 

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Re: [Numpy-discussion] Converting a list

2006-07-10 Thread Nadav Horesh

Do you mean:
>> map(shape, data)

-Original Message-
From:   [EMAIL PROTECTED] on behalf of Nils Wagner
Sent:   Mon 10-Jul-06 12:26
To: numpy-discussion@lists.sourceforge.net
Cc: 
Subject:[Numpy-discussion] Converting a list

Hi all,

I have a list consisting of arrays of different size

data =  [array([-1.+0.j, -1.+0.j, -1.6667+0.j]),
array([-2.+0.j, -2.-0.6667j, -2.-1.j]),
array([-2.-2.j, -1.-2.j, -0.6667-2.j]), array([
0.-2.j,  0.-1.6667j,  0.-1.j]), array([ 
6.12323400e-17-1.j,  -2.58819045e-01-0.96592583j,
-5.e-01-0.8660254j ,  -7.07106781e-01-0.70710678j,
-8.66025404e-01-0.5j   ,  -9.65925826e-01-0.25881905j])]

type(data) =  

shape(data) results in

shape(data) =
Traceback (most recent call last):
  File "sinai.py", line 107, in ?
p = polygon(P)
  File "sinai.py", line 67, in polygon
print 'shape(data) = ',shape(data)
  File "/usr/lib64/python2.4/site-packages/numpy/core/fromnumeric.py",
line 258, in shape
result = asarray(a).shape
  File "/usr/lib64/python2.4/site-packages/numpy/core/numeric.py", line
119, in asarray
return array(a, dtype, copy=False, order=order)
TypeError: a float is required

Is this a bug ?

Nils



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[Numpy-discussion] Fortran 95 compiler (from gcc 4.1.1) is not recognized by scipy

2006-06-01 Thread Nadav Horesh
I recently upgraded to gcc4.1.1. When I tried to compile scipy from today's svn 
repository it halts with the following message:

Traceback (most recent call last):
  File "setup.py", line 50, in ?
setup_package()
  File "setup.py", line 42, in setup_package
configuration=configuration )
  File "/usr/lib/python2.4/site-packages/numpy/distutils/core.py", line 170, in
setup
return old_setup(**new_attr)
  File "/usr/lib/python2.4/distutils/core.py", line 149, in setup
dist.run_commands()
  File "/usr/lib/python2.4/distutils/dist.py", line 946, in run_commands
self.run_command(cmd)
  File "/usr/lib/python2.4/distutils/dist.py", line 966, in run_command
cmd_obj.run()
  File "/usr/lib/python2.4/distutils/command/build.py", line 112, in run
self.run_command(cmd_name)
  File "/usr/lib/python2.4/distutils/cmd.py", line 333, in run_command
self.distribution.run_command(command)
  File "/usr/lib/python2.4/distutils/dist.py", line 966, in run_command
cmd_obj.run()
  File "/usr/lib/python2.4/site-packages/numpy/distutils/command/build_ext.py",
line 109, in run
self.build_extensions()
  File "/usr/lib/python2.4/distutils/command/build_ext.py", line 405, in build_e
xtensions
self.build_extension(ext)
  File "/usr/lib/python2.4/site-packages/numpy/distutils/command/build_ext.py",
line 301, in build_extension
link = self.fcompiler.link_shared_object
AttributeError: 'NoneType' object has no attribute 'link_shared_object'



The output of gfortran --version:

GNU Fortran 95 (GCC) 4.1.1 (Gentoo 4.1.1)
Copyright (C) 2006 Free Software Foundation, Inc.

GNU Fortran comes with NO WARRANTY, to the extent permitted by law.
You may redistribute copies of GNU Fortran
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING

I have also the old g77 compiler installed (g77-3.4.6). Is there a way to force 
numpy/scipy to use it?

  Nadav






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