Questions tagged [precision-and-accuracy]
The precision-and-accuracy tag has no usage guidance.
546
questions
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1answer
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The value of the function with a very small Imaginary part but can be Plotted
I have a function Y[x_,β2_], It can be plotted normally. But when I take specific values, I get something like +0.000000*I when ...
4
votes
2answers
171 views
Slider changes Pi to a MachinePrecision number
Problem
Consider the following code:
DynamicModule[{a = {0, Pi}, b = 4},
{Slider[Dynamic@b, {a}], Dynamic@b}
]
I want a Slider...
0
votes
1answer
67 views
Accurate Numerical values of a given functional
Consider the following functional :
$$
I(x,s) =\int_0^\infty\mathrm dy \frac{F(x + \mathrm iy, s) − F(x −\mathrm iy, s)}{\mathrm e^{2πy}-1},
$$
where $ F(z, s) = \dfrac{\sin^2[π\Gamma(z)/(2z)]}{z^s} $....
0
votes
0answers
33 views
How to copy and paste numbers with “`” mark and use them in calculations, without using N or setting precision every time
Suppose we have run a calculation and get a number like
2.758952615889003`
If we then copy-paste this number and do a calculation like
...
2
votes
1answer
20 views
1
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2answers
87 views
How do you overcome recursion limits when using DSolve?
I have the following program to solve for the neutron to baryon ratio during BBN. I've replaced many of the derived values with constants in order to focus on the problem:
...
0
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0answers
42 views
3
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0answers
72 views
0
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2answers
57 views
Precision in Integrals and NDSolve
I have a simplest code for NDSolve, the problem is I am dividing two small numbers, the denominator is so small that it gives me infinity as an answer, how can I increase the precision to get a ...
22
votes
3answers
9k views
5
votes
1answer
79 views
Find the number of correct digits to compare approximation with exact value
A) For simple example suppose i want to approximate $\pi$ using $\frac{22}{7}$ and $\frac{355}{113}$.
...
1
vote
2answers
123 views
Why can't Mathematica express a minus operation between two decimal numbers with several places? [closed]
A example of the problem. This is a print from mathematica with the demonstration of the issue.
3
votes
1answer
41 views
How to set Working Precision/ Accuracy global for the entire notebook in mathematica
F1[r]=((37.3042 - r) (-25.578 + r) (62.8822 + r))/(3000 r)
FindMaximum[F1[r], r]
The output is {0.0345106, {r -> 31.0723}}.
...
1
vote
1answer
46 views
10
votes
1answer
91 views
How to control floating point precision when `Export`ing to obj format?
Suppose we have a MeshRegion that we want to export to an obj file with, say double precision. Is that possible with Export? And ...
0
votes
2answers
36 views
How to export InputForm of a number
I need to export full form of a number i.e. the actual form with which Mathematica works. For example, full form of a number is
...
0
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0answers
84 views
Why can't NDSolve(Value) solve Maxwell eq. for plane wave i.c.'s when going to spherical coordinates (it works fine in Cartesian coordinates)
I would like to use NDSolveValue (or NDSOlve) to solve a set of PDEs in spherical coordinates. I started with a simplified example that resembles the problem I actually want to study, but where I know ...
2
votes
2answers
89 views
Most efficient strategy for integrating over removable poles?
I am finding many situations where I have to numerically integrate some function $f(x)$ of the form:
$$f(x)=f_{s}(x)-ax^{-n},$$
where $f_s$ is a special function with a finite-order pole that is ...
2
votes
1answer
78 views
Shouldn't NIntegrate return a number whose Precision is PrecisionGoal, not WorkingPrecision?
I know that Mathematica has great built-in precision tracking, so when you do calculations with arbitrary-precision numbers, Mathematica keeps track of the precision on the result. Given this careful ...
3
votes
3answers
138 views
How to convert a real number to a string only in the original length?
Example: I have this number
num = 2.9525730420542016*10^1798
(* 2.952573042054202*10^1798 *)
If I want to convert it to a string, I don't get "2....
3
votes
1answer
46 views
Rationalizing only specific terms in an expression
How can I change an expression like
A = (-1. a)/(x + y) - (2.1 b)/(x + y) + 4.1 + 2. x + (3. r s)/(x + y)
so that -1. a becomes ...
2
votes
1answer
63 views
Problem with the precision
I am trying to plot eigenvalues of a matrix.
I get some errors like “precision may be lost”.
As a result, there are some unwanted jumps in the plot.
Any suggestion of what am I doing wrong?
Thanks
1
vote
2answers
65 views
Accuracy of Mod[x, 1] and FractionalPart[x]
The difference between exact and numerical computation is clear to me. But why is
...
8
votes
2answers
244 views
Computing separatrix orbit
I would like to numerically compute the separatrix orbit for a particle in a few potential wells, given by the negative of
...
0
votes
0answers
31 views
How to avoid machine underflow for plotting and integrating?
I am trying to integrate the following integrand, which I have plotted:
...
1
vote
1answer
72 views
Lowest Eigenvalue of a large sparse matrix without choking up the RAM (Corrected) [closed]
I am trying to find the lowest eigenvalue of a large sparse matrix of dimension N (=$3^n$, where n is number of particles in system ) using ...
2
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4answers
219 views
1
vote
1answer
37 views
Problem with label and precision
I need to define a function that depends on a variable taking values on discrete values, for example:
...
2
votes
1answer
161 views
(Numerical) calculation of nested integrals
The problem
I'd like to (numerically) compute nested integrals of the type $$I(a;k) \equiv \left( \prod_{i=1}^k \int_0^\infty \mathrm{d}x_i \right) \exp \left( - \frac{1}{4a} \sum_{i=1}^k \left( x_i - ...
3
votes
0answers
43 views
Behavior of $MinPrecision seems to have changed between 12.0.0 and 12.1.1
I am running into a very weird bug where setting $MinPrecision to some value (in this case 200) has a very different and ...
1
vote
1answer
91 views
Exported Excel File - decimals
Im trying to export data from the interpolating function result to excel.
everything works fine and the plots are as expected, but if I want to export these data to excel using
...
3
votes
2answers
94 views
Why is DistributeDefinitions taking so long with 100-300 Mb constants?
Why does DistributeDefinitions take so long to distribute variables that are 100-300 Mb in size?
I am setting up ParallelTable ...
0
votes
2answers
142 views
Can someone please comment on the efficiency of Mathematica, Maple and Matlab in conditional plotting?
I use Mathematica to plot
...
1
vote
2answers
66 views
How to make sure that the number of PlotPoints is sufficient for giving the complete result? (How to have a plot of the whole solutions?))
I want to see the domain in which function $f$ is positive. I use this code
...
0
votes
1answer
71 views
Why is this integral throwing a “MemoryAllocationFailure” error?
The following call to NIntegrate throws the error:
Throw::sysexc: Uncaught SystemException returned to top level. Can be caught with Catch[[Ellipsis], ...
5
votes
2answers
126 views
Wish to compute ln(x) with millions of digits of precision fast as possible
Computing $\ln(10)$ to 6 million digits of precision on my 2.5 GHz machine running Mathematica 12.1 takes about 23 seconds using the methods below. Wish to compute $\ln(x)$ with much higher precision....
0
votes
0answers
25 views
FindRoot does not satisfy PrecisionGoal but gives no error message
I use FindRoot to find a root to the equation
...
0
votes
1answer
54 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:
...
1
vote
1answer
67 views
Export high precision data to HDF5
Recently, I would like to use HDF5 instead of CSV because of times Import taking.
Especially, I have to manage large data with high precision (about 50 degits) and ...
1
vote
1answer
38 views
How to improve the accuracy of the data involved in the calculation?
I want to draw the error of the two iterative methods.
...
asked Oct 2 '20 at 0:10
A little mouse on the pampas
5,1602 gold badges9 silver badges27 bronze badges
0
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0answers
33 views
Improve numerical integration precision for multi-dimensional Integral
I have the following 4-dimensional integral
...
0
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0answers
66 views
Significant digits
I have a rather silly question, so please excuse me=)
Let's say I have a general Mathematica code, where I numerically evaluate and combine several quantities. I would like to know how to determine ...
7
votes
4answers
319 views
Why do isolated large values of WorkingPrecision fail in NDSolve?
Executive Summary:
Getting an accurate answer often depends on setting the WorkingPrecision high enough. Once it is high enough, though, I would expect that its ...
1
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2answers
61 views
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2answers
38 views
Expression evaluates to a different number when made a function
The following expression evaluates to zero at large n when just using replacement, but if the same expression is defined as a function ...
2
votes
1answer
79 views
Precision on FindRoot
I am trying to solve a non linear system of equation, and when I solve it, I have the following message
FindRoot::lstol: The line search decreased the step size to ...
1
vote
4answers
142 views
Can I change the default behavior so that “0.1” is interpreted as “1/10” automatically?
Consider the function
f[a_] := NIntegrate[Sqrt[a + Log[x]], {x, 1, 10}, WorkingPrecision -> 30].
With this definition, I cannot call ...
0
votes
0answers
38 views
Increase precision of ConvexHullMesh
I want to generate a set of equations for all planes in the convex hull as specified in this question. The problem is that the generated set of equations don't correctly cover all the points. I run a ...
1
vote
0answers
32 views
When do errors stop calculations? [closed]
When plotting Plot[Exp[-1/(1 - (x + 10)^2)], {x, -11, -10}], I get the following warning
but the Plot follows. However, if I ...
2
votes
2answers
82 views
