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May
27
comment Integral equation
This is not really an integral equation. The upper limit of the integral has to be z in your example, which is the independent variable in f(z) for it to be called integral equation? How did you handle the derivative of the absolute term there?
May
26
comment Listing elements starting from 0
@Prahar There is nothing wrong with using these options for small code. But I was thinking when the code gets larger, and you have many functions, it can get confusing if some code uses index 1 and another uses index 0. Also the Notation package option requires loading it each time. So this makes it harder to share code with others. But you try them and decide if these work for you. See this note on the subject.
May
23
comment Solution to $y = x^x (1-x)^{(1-x)}$ for $x$
@Guesswhoitis. I agree. This is a math question really, not Mathematica.
May
23
comment Solution to $y = x^x (1-x)^{(1-x)}$ for $x$
@Guesswhoitis. yes, but that is what I mean, now solve for $x$ from the above, and take series expansion of the RHS, then equate the $x$ coeffcients. There will be one term in the series with $x$ in it. That is what I meant.
May
23
comment Solution to $y = x^x (1-x)^{(1-x)}$ for $x$
How taking the logs of both sides, then separate $x$ by itself in terms of all the others terms (which will have $x$ in them), you get $x=\frac{\ln(y)-ln(1-x)}{ln(x)-ln(1-x)}$ and then take series expansion of the RHS in $x$, and then equate the $x$ coefficients, so you get $1=\frac{log(x)-log(y)}{log(x)^2}$ and now solve this for $x$ which gives E^(1/2 (1 - Sqrt[1 - 4 Log[y]])) with complicated conditionals. warning, I am not a math major, since the above might not make sense math wise, but something to look at.
May
21
comment NDSolve and assuming
on use of assumptions: DSolve and NDSolve do not use assumptions themselves. I can't find the reference on this now, but this came up before. Here is dsolve-will-not-apply-assumption question on assumptions with DSolve
May
20
comment Roots of Whittaker W function
@Guesswhoitis. I did try it before commenting. They are tiny and they all went away after Chop. V 10.1
May
20
comment Roots of Whittaker W function
One issue is that they all have a nonzero imaginary component To clean, use Chop it is floating point computation noise.
May
20
comment How can I mark a point on a slider control?
@glance the tick is the control variable used to control everything. a control variable has to appear in the Manipulate expression somewhere to be tracked.
May
20
comment Are there any open source projects related to signal processing
You can't buy the DSP app anymore. I have it since I bought it long time ago, but it does not run anymore on new versions of M. Check this site which I think is the origin of that application from long time ago by Brian Evans.
May
20
comment Are there any open source projects related to signal processing
There used to be Mathematica DSP application, but most of that functionality are integrated to Mathematica now (not open source ofcourse ;)
May
20
comment Is there a way to separate variables between multiple notebooks?
@ShutaoTang I do not know. But if you ask at Mathworks Answers forum or at comp.soft-sys.matlab someone there should know.
May
18
comment Discrepancy in the series expansion of $\log(z/(z-1))$ in Mathematica 5
Yes, I think M should have the sign function there. I verified with Maple, Maple gives this: series(log(z/(z - 1)), z=0); ln(z)+I*csgn(I*z)*Pi+z+(1/2)*z^2+(1/3)*z^3+(1/4)*z^4+(1/5)*z^5+.... notice the I*csgn(I*z) there, which is explained more here
May
18
comment ParametricNDSolve without initial condition?
But help shows how to use the result? The examples all show how to use it. Is the question about how to use the result or something else?
May
18
comment Choosing FEM element type and mesh refinement
fyi, I copied the code from the notebook. To do this in the future, convert the cells to InputForm and then copy as text and paste here as code.
May
15
comment Internal coupling of Fortran and Mathematica codes
I have no experience with FORTRAN programming Well, you can ask about how to write the Fortran in the Fortran forum. (btw, it is Fortran now, not FORTRAN, the name was changed 25 years ago to indicate modern Fortran :). As I mentioned above, all what you have to do is compile it to an exe (use gfortran, or ifort or any Fortran compiler). Then run it from Mathematica using the RunProcess command. All of this is really straight forward. All what you have to do is write the data from Mathematica (there are number of ways to export data from M) to a text file and read the data from Fortran.
May
14
comment $\mathbf L\mathbf D\mathbf L^\top$ Cholesky decomposition
Here is the LAPACK Fortran implemenation using what is called Bunch-Kaufman diagonal pivoting method for LDL^T factorization for real symmetric (not necessarily positive definite) matrix. I think Mathematica should have an LDL special decomposition. Matlab has one here.
May
14
comment Internal coupling of Fortran and Mathematica codes
If the Fortran program is a stand alone, you can generate the output from your Mathematica script and export the output to a text file, then at the end of the script use the RunProcess command to invoke the Fortran executable, but change the Fortran program to read its input from the text file generated by the Mathematica script. Make sure they reside in the same directory to make it easier to locate the file used to communicate between them. direct Fortran function calling would need using mathlink and is more complicated.
Apr
13
comment Drawing nodal lines of wave equation
@Pickett it is not an answer, that is why it is a wiki.
Apr
13
comment string and subscript in label
fyi, I am not sure that using tab "\t" is recommend for spacing, as it might generate different space amount depending on the platform or some other system configuration. I think Spacer[n] is supposed to generate the exact space on all systems. (mac, linux, windows)