Patrick Da Silva

less info
170 reputation
19
bio website facebook.com/paterz1
location Montreal, Canada
age 23
visits member for 2 years, 1 month
seen Sep 8 '13 at 15:42

I completed my second year of studies in mathematics at University of Montreal. My current interests are number theory, analysis, measure theory and abstract algebra.


Apr
8
awarded  Notable Question
Nov
21
awarded  Nice Question
Sep
8
awarded  Popular Question
Sep
21
awarded  Custodian
Sep
10
accepted Trying to plot ugly expression, not working
Sep
10
comment Trying to plot ugly expression, not working
I just saw that the typo was also in my question. It was really just a transcription mistake though because I've always been able to plot the first equation, it was with the second one I had trouble. And you helped! Thank you again. +1 & check!
Sep
10
revised Trying to plot ugly expression, not working
added 12 characters in body
Sep
10
comment Trying to plot ugly expression, not working
I found the typo in your code! The curves now perfectly match. The curve in brown is actually the original one, the right line for 'equation' was equation = ComplexExpand[ Abs[A[z] + (3 z + z^2)/A[z] + z] - Abs[rho A[z] + rho^2-----> (3 z + z^2)/A[z]<------ + z] /. z -> x + I y, TargetFunctions -> {Re, Im}];
Sep
10
comment Trying to plot ugly expression, not working
I don't know why in case of equation2 you felt the need to use the command 'TargetFunctions->{Re,Im}'? I must admit I don't know what it does, but I don't see how what you're trying to do is any different from the 'equation' case, where you just wrote 'equation==0' in the end.
Sep
10
comment Trying to plot ugly expression, not working
Sure. I'll give it a try and look what happens. But you definitely don't have the right expression; that curve in brown down there is not natural in the problem. Maybe I typed something wrong when entering the question in Mathematica. I'll double check
Sep
10
awarded  Commentator
Sep
10
comment Trying to plot ugly expression, not working
I really don't understand why you added those two lines though! equation /. {x -> 1.2, y -> 3.4} equation2 /. {x -> 1.2, y -> 3.4}
Sep
10
comment Trying to plot ugly expression, not working
The picture in purple is quite similar to the one I have, except mine was way smoother. The equation you have in brownish looks like the conjugate of the equation in purple. I expected this to happen, but I didn't know about the ComplexExpand command.
Sep
10
comment Trying to plot ugly expression, not working
@belisarius : Sorry yes, I just typed it on MSE a little too fast. But I did put the x + Iy when I tried. I know the expression is a bit ugly but it's just something of the form f(x) = conjugate( f(x) ) rho^2, so if you just remember that f(x) = A[x]...+(3x+x^2)/A[x], I tried something like ContourPlot[F[x+Iy] == Conjugate[F[x+I y]] rho^2, {x,-3,3},{y,-3,3}], and I tried with+without using a function F or the actual expression.
Sep
10
revised Trying to plot ugly expression, not working
added 96 characters in body
Sep
10
comment Trying to plot ugly expression, not working
I guessed that ContourPlot[A[x] Conjugate[x] + Conjugate[(3x+x^2)/A[x]] x + Conjugate[A[x]] (3x + x^2)/A[x] == Conjugate[A[x] Conjugate[x] + Conjugate[(3x+x^2)/A[x]] x + Conjugate[A[x]] (3x + x^2)/A[x]] rho^2 ,{x,-3,3},{y,-3,3}] should have worked, but unfortunately it didn't.
Sep
10
comment Trying to plot ugly expression, not working
ContourPlot[ Abs[H[x + I y]] == Abs[J[x + I y]], {x, -3, 3}, {y, -3, 3}] Where H[x_] := AA[x] + (3 x + x^2)/AA[x] + x and J[x_] := rho AA[x] + rho^2 (3 x + x^2)/AA[x] + x. This is the one that worked (using the initial equations, not the re-worked up ones). All my other attempts with the new equation failed, I tried a few using ContourPlot.
Sep
10
comment Trying to plot ugly expression, not working
@R.M : It is utterly simple, but it's really huge, because one needs to expand two products and each product is a product of two factors with three terms, so you end up adding 18 things. But it simplifies really well, you just need to know that (1-rho^2)/(1-rho) = rho+1 = -rho^2 and everything follows naturally. I really considered seriously the answer to your question. If you don't trust me, feel free to check it yourself, but re-transcribing it might end up in transcription mistakes more than anything else.
Sep
10
awarded  Editor
Sep
10
revised Trying to plot ugly expression, not working
added 64 characters in body