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bio website quantum.at
location Vienna, Austria
age
visits member for 2 years, 2 months
seen 2 hours ago

PhD student in Theoretical Physics

Research interests include Quantum Optomechanics and Quantum Optics


Jul
21
comment Matrices and polynomials: MMA 8 vs. 9?
Note that the r[x_] := R[[i]] doesn't make much sense...
Jul
20
comment Sporadic bug in Mathematica 7.01.0 MatrixPower and/or Eigensystem functions on floating-point symmetric matrices with repeated eigenvalues
I just let Mathematica 9 run through more 4 million iterations of your code, without finding a example where it fails. Although it is not indicated in the docs, MatrixPower must have changed between 8 and 9, as the handling of non positive definite matrices is now different. Maybe it was a bug and it has been fixed?
Jul
20
comment Matrices and polynomials: MMA 8 vs. 9?
@nardol5 I'm not quite sure what you are doing then because it gives me 13.1578
Jul
20
comment Matrices and polynomials: MMA 8 vs. 9?
@nardol5 The error message says it all... Try MatrixFunction[Function[x, R[[1]]], T]
Jul
19
revised How can I make ArrayPlot use one pixel per plot point?
rewrote question to express what the OP actually wanted to know
Jul
19
suggested suggested edit on How can I make ArrayPlot use one pixel per plot point?
Jul
19
comment Matrices and polynomials: MMA 8 vs. 9?
It's funny, because the documentation says that MatrixPower was last modified in version 6.
Jul
19
comment Matrices and polynomials: MMA 8 vs. 9?
I think MatrixPower chokes on your matrix not being positive-definite...
Jul
19
comment Can I make V9 prompt witb “In[1]:=” before I enter an expression?
@Nasser So if the notebook interface ever showed that behaviour it was a long time ago :D
Jul
19
comment Can I make V9 prompt witb “In[1]:=” before I enter an expression?
@Nasser I seem to be blind. I just see a In[2]:=... but that just shows the behaviour of version 9.
Jul
19
comment Can I make V9 prompt witb “In[1]:=” before I enter an expression?
@Nasser Where exactly can I see the behaviour the OP described?
Jul
19
comment How can I make ArrayPlot use one pixel per plot point?
This should work ArrayPlot[RandomReal[1,{100,100}],PixelConstrained->True,ImageSize->{100,100}]
Jul
19
comment How can I make ArrayPlot use one pixel per plot point?
ImageDimensions returns the number of displayed pixels not the number of blocks used by ArrayPlot
Jul
19
comment Differential Equation power spectra
@Slightly I don't think that got any clearer. Please try to explain exactly what you want and why the suggested solutions fail in that respect. Best would be to update your post and show what you currently have and the problems you are experiencing.
Jul
18
comment Can I make V9 prompt witb “In[1]:=” before I enter an expression?
Just out of curiosity: Why don't you like the standard behaviour?
Jul
18
comment A rotation-like transform on a matrix
I deleted my comment because I thought I didn't understand what you want, but now I think it was actually valid. What you want can't be done by RotationTransform. Still, I don't understand why this is supposed to be a 90 degree rotation. As @Kuba points out it's a 180 degree rotation + a reflection
Jul
15
comment Gather list elements by index
@PinguinDirk Sure that also works, I would contest it's shorter though. You can do Sort[GatherBy[Transpose[{labels, list}], First], #1[[1, 1]] < #2[[1, 1]] &][[All, All, 2]] then it is shorter, but only by 7 keystrokes :)
Jul
15
revised Gather list elements by index
Jul
15
comment Compile for deployment
That's a pitty. I'm often faced with the problem that I need to send a notebook to one of my collaborators. Often these notebooks use a handful oft functions from several of my packages (maybe only one function per package), and it is a pain to collect all the packages. So the functionality you proposed would be just perfect.
Jul
15
comment Gather list elements by index
@tchronis I realised this is easy to change, see my edit.