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Oct
10
comment Convert matrix of strings to matrix of numbers
s = {"425060", "0.214235E+07", "0.48", "0.01", "0.39", "0.49", "0.01", "0.38", "1.64", "-1.65", "-2.13", "518"}; InternalStringToDouble[#] & /@ s`, see mathematica.stackexchange.com/questions/1737/…
Oct
10
answered what to do when NSolve does not solve
Oct
10
comment Getting unwanted solution from Solve
Solution 3 is a result of solution 2 I do not understand what this means. Each one is an independent solution. You do not obtain one solution from another? Solution 4th is correct. Try: vars = {x[1], x[2], x[3], x[4], x[5], x[6], x[7]}; eqs = {x[7] == 0, 6 x[4] x[5] + 6 x[3] x[5] x[6] + z*x[4] x[7]^2 + z*x[4] x[5] x[7]^2 == 0}; sol = Solve[eqs, vars]; eqs /. sol[[4]] and this gives True. If you want solution over reals only, add the options Reals
Oct
9
answered Total by a criteria
Oct
9
comment Importing multiple files with a loop
what is the first file name? is it datafile.20.0000.out? so what is the last file full name? is it datafile.20.1010.out ? You can't have an index that is not discrete. So index 20.1 will not work.
Oct
9
comment Importing data from Matlab, using data in “NSolve” and send the results back to Matlab
try matlink matlink.org
Oct
8
comment Converting image data to array
use the ImageData[] command img=Import["ExampleData/lena.tif"]; data=ImageData[img];
Oct
8
comment Matrix Rational Canonical Form
@Ryker this was over a year ago. So I do not remember now. But feel free to try it, and you find a bug you can report it and will try to fix it. Make sure to include the input and the expected output to help me fix it. As far as I know the code is supposed to work ok.
Oct
8
revised Using mathematica to understand linear algebra
added color
Oct
8
comment Using mathematica to understand linear algebra
@ybeltukov thanks for the hint. I changed the point to sphere. yes, it looks better.
Oct
8
revised Using mathematica to understand linear algebra
make the point sphere
Oct
8
revised Using mathematica to understand linear algebra
clean
Oct
8
answered Using mathematica to understand linear algebra
Oct
8
comment the default option of NDSolve
You can do Options[NDSolve] and see the default values. It says Automatic for some. Then go to each and looks at its help. For Accuracy it says AccuracyGoal->Automatic normally yields an accuracy goal equal to half the setting for WorkingPrecision and for PrecisionGoal it says ->Automatic normally yields a precision goal equal to half the setting for WorkingPrecision SO they depend on setting for WorkingPrecision Then you look at help for WorkingPrecision
Oct
8
comment Is there a command like meshgrid in Mathematica?
see mathematica.stackexchange.com/questions/30701/… "simulate-matlabs-meshgrid-function"
Oct
8
comment Matrix Rational Canonical Form
@Ryker I do not understand your question. The code is correct, unless you show otherwise. It produces the same result as on wiki, link above.
Oct
8
comment Using mathematica to understand linear algebra
First, you have error in the API, you wrote {{2 x - y, -x + 2y - z, 0 - 3 y + 4 z}, {x, -20, 20}} notice, you included a range specs inside the functions. i.e. you included {x, -20, 20} where it does not belong. Second, what is the parameters you are using? The helps shows that max of 2 parameters can be used, u and v. Are you sure ParametricPlot3D is what you want to use?
Oct
1
comment Outputting numbers symbolically
Table[HoldForm@2^n, {n, 1, 5}] !Mathematica graphics
Oct
1
comment Disable alert message with internet connectivity off
I have the same problem also. But it is a harmless beep that shows up only at start time, so it was easier to just ignore it than try to find how to turn it off :)
Oct
1
comment Why PlotStyle->Dashed make everything dashed?
No problem on windows using 10.01, screen shot !Mathematica graphics