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11 views

Finding the nth digit in a number with k number of digits

Let's say I have the a number $p$ and that is a number that exists of $k$ digits, how can I find a specific digit in that number? For example, I want to find the 10th digit in the number $...
0
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0answers
6 views

Syntax error using Plot

Why is the error coming and what should I do to resolve it
0
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0answers
9 views

How do I decrypt message with RSA algorithm with modulus n = 302446877 and encryption key e 677?

Message: 196512625 25825210 250970710 140420423 22130212 288711674 26343056 Plaintext is grouped in blocks of 4 letters. What I have so far =( ...
0
votes
1answer
18 views

Find barycenter of spectral data

I am trying to find the barycenter of some spectra using numerical integration. I tried to find the wavelength for which the integral splits the spectrum in two equal areas, but the result seems wrong....
-1
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0answers
11 views

Max distance between dots in a given area

I need help with the math problem: in a unit area, I have N(A) tiny dots, the area of each dot is S(A). What is the general formula that gives the maximize distance between these dots? To help explain ...
0
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0answers
23 views

Mathematica Syntax - Mixing commands with text

Simple question but couldn't find answer anywhere.. I'm trying to write a coordinate of a point as such: "(" Subscript[x, k] "," Subscript[y, k] ")" But the output is ...
2
votes
1answer
20 views

Finding the smallest function and the domain on which it is smallest

Given a list of functions what is the best way to find the domains on which each function is the smallest. Simple example ...
0
votes
1answer
16 views

Solve equations for multiple variables at same time

Here is an example equation: Solve[{a*x + b*y == c}, {a}] It gives me: a -> (c - b*y)/x To solve the same equation for <...
2
votes
2answers
34 views

Colouring faces of a graph according to an overlap of edges

I have a basic graph such as the following; ...
1
vote
2answers
44 views

Numerical integration of multidimensional integral

I need to compute quite a few multidimensional integrals with Bessel functions. Here is one example ...
0
votes
0answers
32 views

Strange result for calculating $\Pr \left[ {X > \frac{2}{Y},X > \frac{4}{Y}} \right]$ with $X,Y$ follow exponential distribution? [closed]

First, when I calculate $\Pr \left[ {X > \frac{2}{Y},X > \frac{4}{Y}} \right] = \Pr \left[ {X > \frac{2}{Y}} \right]\Pr \left[ {X > \frac{4}{Y}} \right]$ with $X,Y$ follow the exponential ...
4
votes
1answer
49 views

Stacked/Percentile Bar Chart formatting

There seem to be a lot of questions regarding the formatting of bar charts. Sadly, I couldn't find solutions to my problems, despite all the skimming. Apologies if I missed something. Problem ...
0
votes
0answers
28 views

how to concatenate substitution lists

I'm solving a complex system of equations step by step. And for each of them, I get one of the four solutions q0, q1, q2 and q3, one at a time. Each time with a nice substitution list like : ...
2
votes
3answers
47 views

Display Number with SI prefixes

I have a number of val = 0.000015783 which represents a current value in Amps. I want to display it with 3 significant digits and with SI prefixes instead of the ...
3
votes
1answer
82 views

Why Dot product of my vectors takes longer than usual?

I have a list containing 100 complex numbers lying between 1.9 + 1.9 i and 2.0 + 2.0 i you can download its mx file from the link below and import it in Mathematica: http://adambarfib.ir1.rapidpars....
0
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0answers
27 views

algebra inequality proofs to solve this problem [migrated]

.If a ≥ 0 and b ≥ 0, prove that (1/2)(a + b)≥√ab can i use (a+b)^2=a^2 + b^2 +2ab to get (a+b)^2-(a^2 + b^2)=2ab therefore (a+b)^2 ≥ 4ab then, 1\2(a+b) ≥√ab
1
vote
0answers
54 views

Wolfram Engine for Developers activation/licensing issues

After getting my account I successfully installed the Windows version on Windows 10 and the linux version on Kubuntu 20.04 on a multiboot laptop. However when I tried to install the linux version on ...
0
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0answers
43 views

Making features of an image more prominent

For the image below, would like to make the heavy black downward sloping lines more prominent and the fine gridlines in the background less prominent. Also, would like to provide operations for the ...
0
votes
0answers
29 views

Using ListDenistyPlot to Plot 3 Dimensional List

I have a question regarding how to use ListDenistyPlot. I am trying to plot a large list of data (150,000 data points) by using ...
1
vote
1answer
25 views

Improving The Computation time of a recursive numerical method

I am trying to do a recursive numerical method to solve an ODE in Mathematica. Whatever I try, I cannot get the computation time down. I need to do over 1000 steps, but I cannot get even 20 steps ...
0
votes
2answers
52 views

Using Composite Newton-Cotes integration rules in Mathematica

I am trying to learn how to integrate functions using composite newton-cotes. In other words, I want to divide the interval we are integrating over into $n$ equal subintervals, and then apply Newton-...
0
votes
0answers
36 views

Using output from Solve or Reduce as a value in subsequent equation

I'm trying to run a simulation. I will number sentences to make response easier. (1) Here is my first equation: ...
0
votes
2answers
67 views

How can I plot 2 <= z <= 5 in a 3D graph?

How can I plot 2 <= z <= 5 in a 3D graph? Also, how can I plot only two variables in a 3D graph. For example x = 2, y = 3. I've been using CountourPlot3D and other help but cannot resolve it.
1
vote
1answer
57 views

Subtract peaks from curve

If I have the following data: https://pastebin.com/2jgDw4iQ which plotted using the following code ...
3
votes
1answer
80 views

function over list mathematica

I work on problem that need to define function with two list of data as follow ...
0
votes
1answer
62 views

Exporting a multi excel files into one file

Suppose a list of students'grades in excel: "excel files" I want to write a program separate student grades to their respective classes and then write them in one excel file. What should I ...
2
votes
0answers
49 views

Update Matrix entry from Java

I found the following example online (which works fine) for sending commands from Java: ...
4
votes
1answer
109 views
0
votes
1answer
80 views

Linear diophantine equation

How to use Mathematica to solves any linear diophantine equation of the form ax+by=c, whenever it is solvable. Such as this example, How to get the x = -165, y = 238. Thanks! Link: https://mathworld....
4
votes
1answer
270 views

How to perform a reduced knapsack problem

I have a problem statement that seems to be a reduced version of the knapsack problem, but I don't know how do it in Mathematica. The problem is as follows: Given a set, S, of integers (e.g {a,b,c,...}...
4
votes
0answers
72 views

Insufficient memory problem in Mathematica

I am trying to initialize a 48600 x 48600 packed array from a sparse matrix and a diagonal matrix in Mathematica 8. If S1 is a sparsearray of that size then and S2 is list of 48600 length, then I am ...
0
votes
1answer
41 views

Nested NIntegrate with FindRoot

I am trying to numerically integrate a function using nested NIntegrate: $$F(N,x,s)=\int_{-\infty}^s \int_{-\infty}^{+\infty} K(N,z',x,x') g_{x',s'} dx'ds' $$ where the kernel of the integration, $K(N,...
0
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0answers
44 views

Get a List plot with hep of module

I just want to get a list plot for my model which I wrote with help of the module. ...
0
votes
0answers
58 views

Unexpected results from NonlinearModelFit [closed]

I have attempted to exercise a non-linear model fit to my data, dadtAbs, and got the following puzzle ...
0
votes
0answers
17 views

How does one open/launch UnityLink using Mathematica ver 10 (on Mac)?

I am trying to access UnityLink on Mathematica version 10. When I follow the only found directions, I receive an error that does not inform me on how to resolve the issue. I quote from the notebook: ...
0
votes
1answer
67 views

I want to solve for X in an equation [closed]

I want to solve for X in the equation ode1 (Meaning to leave it alone, or that all the values are on the other side of the equal sign) but the answer it gives me includes to then graph it X vs L but ...
1
vote
0answers
24 views

How do I plot two normalized variables with one varying parameter as a 2d plot or a contour plot?

I'm trying to replicate a plot that has both (x,y) normalized variables, I've tried using Evaluate and Contourplot with no success. I have set Rn=20, but it should be another variable. Where Fn=fs/fr, ...
0
votes
2answers
97 views

Converting a Spherical Polar vector to Cartesian [closed]

I have the vector: $$sin2\theta(cos\phi +\frac 1 2sin\phi)\vec r +2cos2\theta(cos\phi+\frac 1 2sin\phi)\vec \theta +2cos\phi(\frac 1 2cos\phi -sin\phi)\vec \phi$$ in spherical polar coordinates which ...
0
votes
1answer
72 views

Why does this integral of a real, analytic, absolutely integrable function give a complex result?

I am using Mathematica to develop some ``interesting" problems for students to solve using Fourier series. The following computation seems as though it should yield a real result: $B_n = \int_0^1 ...
0
votes
1answer
47 views

Generating a list of outputs using For[] Loop

I have a question regarding the use of the For[] loop to generate a list of outputs from a function that generates random outputs. Essentially, creating a sample of ...
2
votes
1answer
83 views

How to simplify Elliptic integrals?

Context I would like to show that these 2 functions are identical ...
0
votes
1answer
26 views

$MaxPrecision doesn't work

I want to set MaxPrecision low, to like 2 decimals, but after I set it, it stays at 5 regardless. I've tried using two commands: ...
0
votes
0answers
13 views

Is there any formula to get the IRR from the slope of the Cumulative Cash Flow?

I've simulated a monthly regular cash flow with Excel, and the Internal Rate of Return (IRR) calculated from the first date to the current row. The curve of the IRR is very similar to the Transfer ...
1
vote
0answers
22 views
0
votes
2answers
35 views

Expression simplification

I have this term Sqrt[(B Bc)/(A^2-B Bc)]Sqrt[B Bc+A(-A+Sqrt[A^2-B Bc])]Sqrt[-B Bc+A(A + Sqrt[A^2-B Bc])], which actually can be simplified to B*Bc. However, it ...
0
votes
1answer
39 views

$\alpha \int_{0}^T \text{Sin}(fi−fk+Δf)∗t) \, dt$ — Why is it not giving wrong answer? [closed]

$$\alpha \int_{0}^T \text{Sin}(fi−fk+Δf)∗t) \, dt $$ I am integrating this in Mathematica, My code is (1/2)*α*Integrate[Sin[2*Pi*(fi - fk + δf)*t], {t, 0, T}] + Ν1 ...
3
votes
0answers
33 views

Algorithm used by Mathematica for evaluating partial sums

Today, while using mathematica, I entered the command Sum[1/Factorial[n], {n, 0, x}] and found that: $$\sum_{x\geq n\geq0}\frac{1}{n!}=\frac{e\Gamma(x+1,1)}{\Gamma(...
-1
votes
1answer
58 views

Determining intersection point in mathematica plot

I plotted the function given in the figure with respect to "z" .I obtained different plots for different distinct values of "t". Now please can you help how to obtain the ...
0
votes
0answers
86 views

Solving the Schrödinger equation for the hydrogen atom

How can I solve the Schrödinger equation for hydrogen in spherical coordinates in 3 dimensions with Mathematica using DSolve?
0
votes
0answers
44 views

How does one completely scrub everything saved from notebook input into system so that a new evaluation of a notebook starts fresh? [closed]

I tend to code in small chunks before putting it all together into a larger sum that does a lot more. In doing so I often need to erase or delete as much as possible from memory and cache (including ...

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