Questions tagged [numerical-value]

Question relating numerical representations, operations and methods, including approximate results instead of exact symbolic results.

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1answer
58 views

Numerical integration with poles

I have got many errors for this integral. Anyone knows how to fix it? (I am using mathematica12.2) ...
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1answer
69 views

How to get numerical value of functional derivative at specific point

I have a functional in the form: $$F[s(x)]=\int_0^1(s(x)-a(x))^2\mathrm{d}x$$ where $a(x)$ is a parameter function, and I would like to find the functional derivative of $F$ with respect to $s$. ...
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49 views

Double numerical integral, in two steps

Let me define the following function: f[x_] = x I have to solve the numerical integral: ...
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1answer
76 views

Smart way to do a numeric integral of a recursive function defined by symbolic integration

I have a little question. I need a smart way to compute a numerical integral. The standard way to compute a numerical integral, in multiple variables, is, for example, the following: ...
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163 views

Numerical values of Fox H function

I am playing around with the new function from 12.3, FoxH and found the result is not stable. It is interesting that the results are pretty different with the introduction of higher accuracy, and the ...
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1answer
121 views

Numerical integration of a function with Dirac delta

I have a little question about the numerical integration of a function that includes a Dirac delta. I have the following function: ...
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1answer
57 views

Which one is more accurate Solve or NSolve? How can I get the same result as Solve using NSolve in the given code?

I am using this code to calculate the quantity $sol$. Using Solve, I get the result $9.8598$ ...
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1answer
51 views

Getting strange result with derivative of Abs of a complex number

So I am getting some results after a computation like: (-0.741446 - 5.47358 I) Abs'[-0.702207 + 0.0951203 I] The problem is the derivative in ...
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2answers
61 views

Blank plot with numeric data

I seem to be getting a blank plot even though the data provided is clearly numeric and plots fine with other data. I just don't see what is special about this data that results in a blank plot. ...
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74 views

Why does Mathematica store numerical values in a fresh kernel?

For some reason, when I try to do a computation in a fresh kernel, MM remembers the "old" values from the old kernel, is there a way to stop this?
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How to numerically solve this system?

Our system: \begin{align} \dot S &= \mu -\beta_1 S I_2 -\beta_2 S J-\beta_3 S A - \nu S\\[2ex] \dot {I_1} &= p \beta_1 S I_1 +q \beta_2 S J +r \beta_3 S A + \xi_1 J- b_1 I_1 \\[2ex] \dot{...
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Is always possible to define a numerical value using subscript?

In this code I defined some values using subscripts and it is not the first time I did this but strangely the code execution crashes. To follow the code. ...
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66 views

Avoiding underflow with equations of the form $\binom{n}{x} p^a (1-p)^b$

I have the need to evaluate equations of the form $$\binom{n}{x} p^a (1-p)^b$$ where the values of $p$ are between 0 and 1 and $n$, $x$, $a$, and $b$ can be very large numbers. I attempt to use ...
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what's wrong with this code for truncation number m=9?

I have a puzzling problem over the following mathematica code I program to solve some problem. I believe the two plots as defined are identical, but it is only identical when mm<9 and when m is ...
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1answer
53 views

Problem with numerical ConjugateTranspose?

Suppose I have a normalized numerical array, B1, ...
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3answers
46 views

NSolve not giving a solution

I have a parameter set paramFinal2 = {\[Beta] -> 0.2, \[Alpha] -> 0.5 , c -> 0.150, b -> 0.1, \[Kappa] -> 1}; I define the following variable ...
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70 views

Can't create matrix function of symbolic functions and assign values to elements

So I have a problem regarding the symbolic matrix value assignment. Say I create a matrix function as: P[t_]:= {{P1[t]}, {P2[t]}, {P3[t]}}; Then I want to assign ...
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47 views

Numerical minimization of function

So I have the following equation: 3 Sqrt[9.15753*10^-6 + 25.1556 TolC^2 + 25.1556 TolL^2]==1; Now TolC and TolL can take respectively the values of these lists: <...
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Evaluate an expression with numerical values

I hope this time you guys can help me. I have the following numerical expression: ...
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2answers
104 views

Efficent ways to use NSolve, Reduce

hope you're having a nice day! Context: I'm trying to constrain parameters from a model of Orbital Resonance equilibrium. In short, I know a parameter "$\Delta_{eq}$" which is derived from ...
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204 views

Finding the Global Minimum

Consider the function ...
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1answer
90 views

Is there any alternative for NSolve or Solve to obtain all the roots of the given function?

I have this function for reals $0<x<\pi$. $$f(x)=(3 \pi -2 x)^2 \sin \left(\frac{1}{2} \left(\csc ^{-1}\left(\frac{4 \pi (\pi -x) \csc \left(\frac{\pi ^2}{\pi -x}\right)}{4 x^2-8 \pi x+5 \pi ^...
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How can I make sure if the given function has any roots which are not rational multiples of $\pi$?

I have this function for $0<x<\pi$. $$f(x)=(3 \pi -2 x)^2 \sin \left(\frac{1}{2} \left(\csc ^{-1}\left(\frac{4 \pi (\pi -x) \csc \left(\frac{\pi ^2}{\pi -x}\right)}{4 x^2-8 \pi x+5 \pi ^2}\...
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56 views

NMaximize computes wrong value

This question is a continuation of NIntegrate with a complicated function over the 4-sphere . Now I define a certain new function called "improvement" via: ...
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1answer
39 views

Phenomena between ill-conditioned and well-condtioned

Given that I have the following sparse matrix: ...
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1answer
59 views

how we can extract the value of the solution of a PDE in a point x? (NDSolve) [closed]

Please I need your help, I calculate the solution of heat equation using methode of line This is my code: ...
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1answer
34 views

Indeterminant numerical value of summation

I have the following two-fold summation. ...
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53 views

How to improve the calculation accuracy and speed of double numerical integration?

I want to solve the following double numerical integral: $A=\int _{0.52}^1\int _0^{\infty }\frac{\sqrt{s^2-0.52^2} \sqrt{1-s^2} \left(2 s^2-1\right) \left(\left(2 s^2-1\right) \text{T1}-2 s^2 \text{T2}...
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2answers
89 views

Nested NIntegrate over a region: Numerical Integration not converging

I need to computed two double nested numerical integrals, of which one is defined over a specific region (e.g. a pentagon). I've tried to use a single NIntegrate with four variables, but the result is ...
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1answer
63 views

Function range with numerical method

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1answer
158 views

Does this series converge or diverge?

Let us consider the series $\sum_{n=1}^\infty \frac {\{\sqrt n\}-\frac 1 2} n$, where $\{\cdot\}$ denotes the fractional part of a real number. On the one hand, ...
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89 views

(Urgent) NSolve not working and visualization of solutions

I want to solve a system of three equations and 3 variables numerically with NSolve, but it either takes an eternity and doesn't give me a result or it gives me an error message that the methods ...
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0answers
68 views

NSum complaining of being non-numerical

I am trying to evaluate the sum $\sum_{k,l=1}^{30}\frac{1}{(k^2+l^2+1)^{5/4}}$ so I write NSum[1/(1 + k^2 + l^2)^(5/4), {k, 1, 30}, {l, 1, 30}] but I get a message ...
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1answer
68 views

Non trivial zeros of Dirichlet L function

So I was wondering if I can find some of the non trivial zeros of the Dirichlet-L function using mathematica. What I found out was there is a code ZetaZero[] which ...
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95 views

How to use NDEigenvalue to accurately estimate functional determinants?

Goal: Ultimately, I would like to find a trustworthy approximation for the ratio of the functional determinant of two differential operators using the formula $$ \frac{\text{Det}[\hat{D}_0]}{\text{Det}...
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1answer
203 views

Problem with NDSolveValue

I am trying to solve some 3D PDEs (for example, 3D diffusion equation) with step function or DiracDelta function as initial condition. I know those functions have discontinuity so I use some ...
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27 views

Why NSolve can't solve this equation? [duplicate]

My code: ...
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74 views

Is there already a program that analyzes THz-TDS data in Mathematica?

I plan to write a code that reads the time domain data(sample+reference), performs Fourier transforms, calculates transmissivity, solves the transfer function numerically, and gets complex refractive ...
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1answer
94 views

Solving a system of transcendental equations

I am trying to solve the following system of transcendental equations: ...
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1answer
77 views

How to obtain numerical solutions of a system of two equations with two unknowns?

I have two equations with two unknowns $-10<x<0$ and $0<y<15$ $$3 y \cosh (4 x) \cos (y)+(2 x+5) \cosh (x) \sin (y)=0,\\3 x \cosh (x) \cos (y)-(2 x+5) \sinh (x) \cos (y)=0$$ I would like ...
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1answer
723 views

Is Internal`StringToDouble broken in 12.3?

I believe Internal`StringToDouble was the only way to fast convert string into numbers. Now in V12.3 it was removed: Internal`StringToDouble["1"] ...
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1answer
44 views

Numerical value of Derivative of Dirichlet L function at some particular points [closed]

I want to find the numerical value for the derivative of Dirichlet L function to compare with an another formula. However I am not able to obtain any numerical values. I tried to use ...
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1answer
117 views

Solve using PolyGamma function

I am trying to solve for the value of y. My code is: x = 0.165; f = -Log[y] - PolyGamma[0.5 + 0.2*(x/y)] + PolyGamma[0.5]; Solve[f == 0, y] Running gave me ...
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1answer
109 views

How do I install the " FourierSeries` " package?

Can anyone tell me where are the packages for Wolfram Mathematica 11.2 ? How do I load them?
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1answer
60 views

Is it possible to ask Mathematica to give all the roots of the given function?

I have this equation $$ 36 \cos \frac{3 x}{4} \cos \frac{27 x}{20} \left(\cos \frac{3 x}{5} +2 \cos \frac{21 x}{10} \right)=0 $$ Is it possible to ask Mathematica to give all the roots of the ...
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2answers
65 views

a generic way to deal with intermittent non-numerical values in arrays

Sometimes when dealing with arrays with intermittent non-numerical values (e.g., NaNs imported from external sources), the common arithmetic functions (e.g., ...
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32 views

Mathematica CSV values

I wanted just to add constant to each value. i. e. data = Import["/Users/paul/Desktop/rtm1.csv", "CSV"] And I get ...
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1answer
59 views

NSolve missing solutions

I'm having trouble solving the transcendental equation. For some values ​​of bi, NSolve obtains 6 roots, however when changing the value, it obtains 5. Graphing the function clearly shows that the ...

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