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bio website quantum.at
location Vienna, Austria
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visits member for 2 years, 2 months
seen 7 hours ago

PhD student in Theoretical Physics

Research interests include Quantum Optomechanics and Quantum Optics


Jul
25
comment Simple rule appears not to work
Yes, because rules apply to the FullForm of an expression. If the FullForm does not match then nothing will be replaced. The pattern you use for the replacement is pretty complicated so it is not very surprising that it only matches in a few special cases. Rewrite your rule such that the left hand side is simpler and try again.
Jul
23
comment Isolate a specific contour without Contour Shading
In that case I think one could use p/.Tooltip[_, Except[label]] :> Sequence[] to delete the unwanted lines...
Jul
23
comment Isolate a specific contour without Contour Shading
There is just one thing to do... select the lines corresponding to one value only. But that should be possible by the tooltips. Or maybe even a better way?
Jul
23
comment Solve equation containing conditions (If expressions)
Why don't you just integrate the PiecewiseExpand//Simplify solution in your answer? It was your idea anyway. And I think you can get rid of the obsolete part of the answer, nobody will mind.
Jul
23
comment Solve equation containing conditions (If expressions)
Yes, in version 9 AAA // PiecewiseExpand // Simplify yields dc == -0.00005 || dc >= 2.49955 and AAA // Rationalize // PiecewiseExpand // Simplify gives 1 + 20000 dc == 0 || 20000 dc >= 49991.
Jul
23
comment Solve equation containing conditions (If expressions)
Nice, it's quite amazing that this works. Just an aside: You don't even need the Reduce, a simple AAA // PiecewiseExpand // Simplify does the job (even without the warning).
Jul
21
answered Automatically generated summation region
Jul
21
comment Automatically generated summation region
You could use something like Sum[1,Evaluate[Sequence@@{{i,1,2},{j,1,2}}]]
Jul
21
comment Matrices and polynomials: MMA 8 vs. 9?
@nardol5 I just want to point out that MatrixFunction shows the same behaviour as MatrixPower if asked to compute T^0 (where T is not positive definite), which caused your code to fail in the first place! Try MatrixFunction[#^0 &,T].
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?