Questions tagged [numerical-value]
Question relating numerical representations, operations and methods, including approximate results instead of exact symbolic results.
1
vote
2answers
49 views
Numerics & List Manipulation:ListCorrelate: yield $\{-f1 + f2, \dots, -f2 + f4, \dots\}$ from $\{f1, f2, f3, f4, f5\}$
The command
ListCorrelate[{-1, 1}, {f1, f2, f3, f4, f5}]
yields
{-f1 + f2, -f2 + f3, -f3 + f4, -f4 + f5}
is there any simple way to get
{-f1 + f2, -f1 + ...
2
votes
2answers
182 views
Help for Solving Two Equations For Two Unknows (from a Paper)
I am trying to reproduce numerically the results found in this paper: https://ieeexplore.ieee.org/document/1707778
You don't necessarily need to read it. Basically I boils down to solving a two ...
0
votes
4answers
106 views
How to solve equation in integer numbers
I would like to solve an equation like this $\frac{\log(2)}{\log(3)}=\frac{n-0.5}{k-0.5}$ where $n$, $k$ are positive integers and $\log$ is natural logarithm. Of course, I can do only numerical ...
1
vote
2answers
97 views
Sampling data from numerical values of density distribution of nucleons
How could i sample my data which follows distribution if i have only numerical values of density distribution as an example data attached as in picture
I tried but do not know how to do it.
The data:...
0
votes
3answers
26 views
Low precision from function returning matrix
Got a function depending on single parameter "t" defined below which
returns a 2 by 2 matrix
...
1
vote
1answer
69 views
Second-order nonlinear boundary value problem
I am trying to follow this work, in which Eq. (11), the 2nd-order, nonlinear differential equation depends on a pair of parameters $ (\kappa, h) $. But now I only care about the case with a vanishing $...
3
votes
1answer
98 views
Solve a system of 4-th order polynomial equations (numerically)
I have a function defined on $ S^6 \times S^6 $ (two spheres embedded in $ \mathbb{R}^7 $ individually). Let us call this vector $ \vec{f}(\vec{x},\vec{y}) $, where $ \vec{x} $ and $ \vec{y} $ are ...
3
votes
1answer
42 views
Numerical precision problem
I have this simple code:
ep = 1 - 80000000000 (-(199999/200000) + 1/E^(1/200000))
ep // N
-8.27404*10^-8
...
1
vote
0answers
35 views
Finding zero linear combinations of polynomials (numerically)
I have two functions of real variables defined on two compact spaces
...
0
votes
1answer
26 views
Best practice when encountering “Indeterminate” when applying a value equal to infinity
I have the following equation, which equals 1 for positive values of $n$, but at $n = \inf$ the equation becomes indeterminate.
4 n (1 - 1/2) 1/2 (1/Sqrt[n])^2
...
3
votes
1answer
65 views
Why does NSolve give different results in different version of Mathematica?
I am working on a problem with a colleague who uses Mathematica v.10.2 while I have v.11.0 Student Edition. We are solving the exact same equations but get two slightly different results. Why would ...
2
votes
1answer
46 views
Numerical solution of a system of two exponential equations
I need to solve this two equations for x and y:
...
1
vote
2answers
60 views
Solving a system of equations with numerical approximation [closed]
Let a, b, c be vectors obtained with the function N and x, y be scalars. I have the equation:...
-1
votes
1answer
42 views
0
votes
2answers
63 views
equal expressions give different numerical result
I have two expressions, and they are really equal:
...
0
votes
0answers
21 views
Raising a negative number to a fractional power, why the result is different? [duplicate]
In the math theory, we know have
$$(x)^{\frac{m}{n}=}\sqrt[n]{x^m} \ ,$$
it means
$$(-1.5)^{\frac{1}{0.3}}=(-1.5)^{\frac{10}{3}}=\sqrt[3]{(-1.5)^{10}}=\sqrt[3]{1.5^{10}}\simeq 3.8634 \ .$$
But in ...
3
votes
0answers
148 views
On Ж, and the fine-structure constant
I'm trying to reproduce the results from a certain infamous paper that has been moving around the web for the last few days. The details are irrelevant.
This paper claims to have a closed-form ...
0
votes
1answer
75 views
How to get more digits from Fit
Taking the example from the Mathematica documentation for Fit, consider the following
...
0
votes
2answers
86 views
Product of large number with a very small number returns zero because Mathematica sets the very small number equal to zero [closed]
I have a product Exp[-I*Pi*x]*BesselK[-1, 2.43*Ix]. Now, Exp[-I*Pi*x] grows larger and larger as $x$ increases for imaginary ...
2
votes
0answers
43 views
What is the acceptable error in numerical calculations? [closed]
I am doing a calculation where I try to simplify a very complicated complex function. I did this step by step and I checked that the numerical values that the function gets for certain values of the ...
0
votes
1answer
64 views
Taylor Series of numerical solution of FindRoot
I have found the inverse to the following equation by using FindRoot. I want to have a Taylor approximation (say starting from ...
6
votes
4answers
114 views
Suppress trailing 0s in numerical values
For example, this is what I want
In[1]:= N[Table[4^(i/4), {i, 1, 4}]]
Out[1]= {1.41421, 2., 2.82843, 4.}
But if I want a few more digits only from the irrational ...
1
vote
0answers
44 views
Is there a function that returns me the largest common divisor? [closed]
Is there a function that returns me the largest common divisor?
I tried this:
Intersection[Divisors[200], Divisors[280]] // Last
0
votes
1answer
96 views
How to test if a solution of NDSolve is positive
I want to solve a differential equation numerically and determine one of the parameters in the D.E. The goal is to determine $M$ such that the function goes asymptotically to zero or to put it in a ...
0
votes
2answers
67 views
Computing a sum with high precision
I am aware that a similar question has been asked, for example, here and here, but none of the proposed solutions solves my problem, so please wait before you mark this question as a duplicate.
...
1
vote
1answer
65 views
How do I to remove a factor of 1 [duplicate]
I evaluated
Subscript[ε, 1, 2] = 0.5 Subscript[γ, 1, 2]
2 μ Subscript[ε, 1, 2]
1. μ Subscript[γ, 1, 2]
How do I to remove ...
1
vote
1answer
60 views
How to make Mathematica show small and large results? [closed]
I have two equations with x=r+Log[-1+r] and v=(1-1/r)/r^3 forms. When I substitute ...
1
vote
0answers
35 views
Getting the coordinates of a specific point out of a plot [closed]
I have the following piece of code that in the first part calculates and plots a function and it uses it in the second part to perform an NDSolve. After that I am plotting two functions. What I would ...
0
votes
0answers
50 views
Fastest way to find roots and reproduce this result
I am trying to solve the following transcendental equation numerically with the given values and to reproduce the diagram attached below.
$0=\frac h2\sqrt{\left(\frac{\omega\cdot n_1}c\right)^2-\...
3
votes
1answer
76 views
How to avoid rounding error, when exporting numerical values
How to avoid the rounding error, when exporting data like this:
ra = Range[0.004, 0.074, 0.0005];
Export["range.txt", ra]
The result is this:
2
votes
0answers
77 views
How solve this equation and plot the results?
I want to solve the following function and get values for $\omega$.
$$\omega - \omega_{21} + i/\tau_{2} - s_{1}\alpha_{1}(\omega)[1+f(\omega)] = 0$$
The function $f(\omega)$ is the troublesome ...
1
vote
1answer
38 views
Numerical solution to integration of function which parameters define the integral limits
I have following equation:
$\int^{\delta_c}_{\delta_c-\pi}\sqrt{h^2_c(\cos(\delta_c)^2-\cos(\delta)^2+\Omega_c(\delta_c-\delta)}\text{d}\delta=\pi$,
where $\delta_c=\frac{1}{2}\arcsin\left(\frac{\...
2
votes
1answer
70 views
Numerical artifacts appearing ONLY on boundary of 3Dplots and not on Plot
I have a behavior with 3D plots I really don't understand and I would like to correct it.
I have a 2D function to plot, here is its graph with Plot3D :
We can see that on the top boundary of $\Delta ...
1
vote
1answer
98 views
11
votes
3answers
622 views
Solve Laplace equation in Cylindrical - Polar Coordinates
Hey mathematica stackexchange!! I've got a (possibly stupid) problem. I've tried many things to no avail, and I've read every post I've found on Laplace's equation.
Background:
I'm trying to find the ...
3
votes
1answer
125 views
How to make Mathematica substitute exact numerical values of (derivatives) 2F1
I have a long output that contains Taylor expansion of some function. Some of the coefficients are combinations of the (derivatives of) 2F1 at nice integer values of the coefficients. I can see that ...
1
vote
1answer
72 views
Numerical error in compile, Strange behaviour in numerical evaluation
First of all, apologies for the large numbers, I couldn't find a working example for a far lower order and the zeros are necessary...
my problem is this:
I have a large polynomial (from high-order ...
1
vote
1answer
56 views
Partial Derivatives of numbers not evaluating?
I have code of the form
someFunction[xx_?VectorQ] := 1 + anotherFunction[xx]
myfunction[xx_?VectorQ]:= Sum[D[someFunction,xx[[a]]],{a,1,4}]
After this evaluates, ...
2
votes
0answers
50 views
How to convert a dollar fraction into a normal dollar amount
I'm trying to use Mathematica to compute compounded interest. I used Wolfram Alpha, and it gave me the code
...
1
vote
1answer
55 views
Function not evaluating to zero - numerical errors
I have a complex but analytical expression that should always evaluate to zero for certain values, but I'm getting strange numerical noise I think I can avoid. The problem seems to occur in a ...
1
vote
1answer
26 views
Setting the parameters in a defined function vs replacement rule in the formula
I have the following definition in my Mathematica notebook.
...
3
votes
1answer
103 views
Error in integral representation of Appell's series
It was originally asked here.
According to About the confluent versions of Appell Hypergeometric Function and Lauricella Functions the integral
$$\int_0^1t^{a-1}(1-t)^{c-a-1}(1-xt)^{-b}e^{yt}~dt $$...
0
votes
0answers
108 views
Solving Laplace equation in cylindrical coordinates, manipulating the result
just for the demonstration (the exact details of the problem don't really matter), I'm solving the following PDE:
$$
\text{inner cylinder: } r = 1, \; h = 1, \text{ centered at origin}
$$
$$
\text{...
2
votes
1answer
34 views
Question related to IntegerPart
I am having trouble understanding the following result:
Through[{IntegerPart,FractionalPart}[{100 4.02}]]
{{401}, {1.}}
...
0
votes
0answers
48 views
Integrate a multivariate function similar to a delta function
I am doing a code in Mathematica. I have the following function:
...
0
votes
0answers
79 views
3
votes
1answer
79 views
Is this bifurcation or numerical error?
I encountered a definite integral (with parameter $k$) that produces the "chaotic" figures below.
$$F(k) \equiv \int_{\theta_k}^{\theta_{k+1}} f(\theta, J \sin\theta - k)\,\mathrm{d}\theta~, \qquad f(...
3
votes
1answer
76 views
Numeric values for MinkowskiQuestionMark
Why NumericQ[MinkowskiQuestionMark[Pi]] returns False? Is it defined only for algebraics? Numerical evaluation gives some number,...
2
votes
2answers
78 views
How to avoid problems with the large imaginary part of LegendreQ?
I am trying to evaluate sums involving LegendreQ[n,x], the n-th order Legendre function of the second kind $Q_n(x)$, at large $x>1$. However, the problem is that ...
2
votes
1answer
79 views
How to get Mathematica to Return an Actual Numerical Result For Probability? [closed]
This is a painfully basic question. It's probably been answered before (or might be in one of the documentation packages), but I've been looking for some time and can't find it! (Though it could very ...
