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Sep
25
answered Plotting (Graphing) a Quadratic Function with Vertex and Roots
Sep
25
comment Plotting (Graphing) a Quadratic Function with Vertex and Roots
Is this what you want: r1 = 15/10 + I Sqrt[7]/2; p = Expand[(x - r1)*(x - Conjugate[r1])] Plot[p, {x, -3, 3}] which gives on V 10.01 !Mathematica graphics the poly is 4-3 x+x^2
Sep
25
comment Manipulating parameters in a complex algorithm
it looks good. Tried it, was little slow when N was 500 and higher. May be this is algorithm tune-up. But if it works for you and no more issues, then you can answer your own question with your answer above. Unless you have any specific questions.
Sep
24
revised Error using Nsolve with system of two equations: “Use Reduce”
added 567 characters in body
Sep
24
comment Error using Nsolve with system of two equations: “Use Reduce”
@DanielLichtblau thanks! I actually did not notice that NSolve accepts ranges, now it works much better. Updated answer.
Sep
24
comment Error using Nsolve with system of two equations: “Use Reduce”
I tried using Ersek RootSearch, which is supposed to be able to find roots in given range, but on V 10.01 something changed. Now I get No more memory available. Mathematica kernel has shut down. Try quitting other applications and then retry. This package looks like it is no longer maintained. library.wolfram.com/infocenter/MathSource/4482 It worked ok on version 9.01
Sep
24
comment Numerical Error with Matrix operations
try Chop[ret]
Sep
24
comment Manipulating parameters in a complex algorithm
To use second argument of dynamics, yes, you create each control using direct Dynamic syntax. For example, for the slider, you use Manipulator etc.. Then add the specific logic right there in the second argument as pure function. This way, the second argument acts like the callback. Much easier to manage. here is an example mathematica.stackexchange.com/questions/42796/… I do all my demos using this method now. I find this method easier to work with.
Sep
24
answered Error using Nsolve with system of two equations: “Use Reduce”
Sep
24
comment Manipulating parameters in a complex algorithm
If you look at this link it summarizes all the different cases for Manipulate. For you example, I would use the second argument of dynamics, it is the most flexible way to handle very complicated events and interactions since it is based on then event/callback way of looking at things.
Sep
24
answered NDSolve giving the wrong solution?
Sep
23
awarded  Popular Question
Sep
23
comment NDSolve giving the wrong solution?
... the one you showed y=-4*x/(1+3*x). The point is, these are singular solutions. There is a singularity in your ode, which is why NDSolve gives a 1/0 error. So, there is nothing wrong with NDSolve. Notice that DSolve did not solve this.
Sep
23
comment NDSolve giving the wrong solution?
do not have time now, but quick comment: you have non-linear ode. A non-linear ode can admit a singular solution (which can't be obtained from the general solution by giving the constants of integration specific values). Another solution is y=-2. Another is y=(-4*((x^4-2*x^2+1)/(x^4+8*x^3+18*x^2+8*x+1))^(1/2)*x^4-20*((x^4-2*x^2+1)/(x^4‌​+8*x^3+18*x^2+8*x+1))^(1/2)*x^3-4*x^4-24*((x^4-2*x^2+1)/(x^4+8*x^3+18*x^2+8*x+1))‌​^(1/2)*x^2-16*x^3-20*((x^4-2*x^2+1)/(x^4+8*x^3+18*x^2+8*x+1))^(1/2)*x-32*x^2-4*((‌​x^4-2*x^2+1)/(x^4+8*x^3+18*x^2+8*x+1))^(1/2)-16*x-4)/(3*x^4+8*x^3+14*x^2+8*x+3) as well as the..
Sep
22
revised Creating a foggy image
typo
Sep
22
answered Creating a foggy image
Sep
22
comment Steps in row reduction?
Only way I know to look into LU more is by using the {lu,p,c}=LUDecomposition[m] call, where c gives the rows used for pivoting as mentioned in the help. You can't tell how to control the pivoting. There is no option there. from reference.wolfram.com/language/tutorial/… it says LUDecomposition, Inverse, RowReduce, and Det use Gaussian elimination with partial pivoting. That is about it.
Sep
22
comment Is this integral solvable?
You can try the free Wolfram cloud, it has Mathematica there for free wolfram.com/programming-cloud/pricing click on the free option. Also can try Wolfram alpha, it is supposed to be able to do integration as well.
Sep
22
answered Different results of a definite integral $\int_0^{\cosh ^{-1}(a)} \frac{1}{\sqrt{a^2 \text{sech}^2(x)-1}}\, dx$
Sep
22
comment How to remove error at large time in NDSolve
it works ok for me using V 10.01 on windows. moved the slider all the way to the right and I see no errors. !Mathematica graphics may be you can upgrade to 10.01