Questions dealing with the relative uncertainty in the values computed, stored, or manipulated by Mathematica.

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0
votes
0answers
21 views

N[variable,2] displays 6 digits [duplicate]

The following code doesn't behave as I expect. Rather than getting 2 digits upon varying r, I get the default value of 6 digits. What's up? ...
2
votes
3answers
75 views

How to set/adjust Precision for an iterative calculation?

How should I restructure this code? I generate a high-order polynomial poly with integer coefficients, then find roots and divide them out of poly one at a time. ...
6
votes
1answer
148 views

Bug in ListPlot?

I want to check if this is a bug before I email WR about it. I can't get ListPlot[] to make scatter plots over a very small area: ...
4
votes
0answers
73 views

Why has Version 10.3 precision reduced?

In version 7.0.1.0 and versions 10.0 and 10.1 the following is produced: ...
0
votes
1answer
55 views

Lack of precision in solar declination leads to odd Fourier result

Here's the sun's declination for a 10 year period (roughly 2000-2010): ...
0
votes
0answers
36 views

Maintaining working precision in my program

I am badly stuck with this program I am writing. I want output of program below to be precise up to 25 digits after decimal point. I am supplying all inputs with precision 25. But after each iteration ...
0
votes
0answers
30 views

How to fill in missing points on a graph? [duplicate]

If I plot the function Plot[Surd[x, 10], {x, 0, 10}, PlotRange -> {{-3, 3}, {-2, 2}}] I get This issue I have is that graph does not extend down to the ...
3
votes
1answer
139 views

A difficult precision problem

I need to calculate values of a highly nonlinear recursive function, and I am confused by the results Mathematica is returning. ...
1
vote
1answer
84 views

How can I increase the precision of my computation?

How can I increase precision up to 15 digits for the results (EC, and that of FindRoot) computed below? ...
2
votes
2answers
100 views

How can I increase the precision of my table?

I want to see first 15 digits for the values in the table computed below. ...
0
votes
2answers
79 views

Exact calculating the multiply of two real [closed]

As the machine calculate,the exact calculating with real number have some problem to puzzle me long time.We know the 0.142*0.36523=0.05186266 is exactly equalized ...
0
votes
1answer
47 views

Why won't something print with desired precision in a while loop?

I have a problem: when I ask something to print with precision P, that is, Print[N[something, P]], it does not print with precision P, just with the usual output precision. In particular, I have a ...
3
votes
1answer
77 views

Is there any way to use compile and still maintain high precision in Mathematica? [duplicate]

Is there any way to use compile and still maintain Arbitrary-precision like 50 in Mathematica?
3
votes
1answer
42 views
13
votes
2answers
445 views

more numerically accurate inverse matrix

I encountered the following matrix mat = {{2, 2.161209223472559` + 1.682941969615793` I}, {2.161209223472559` - 1.682941969615793` I, 2}} and ...
0
votes
1answer
87 views

Precision of Eigensystem? [closed]

I was using Eigensystem to obtain the rotation matrix. However, I find out Mathematica does not fully diagonalize my matrix (or say not precise enough). My matrix ...
1
vote
0answers
66 views
-1
votes
1answer
54 views

Solve Numerical Equation [closed]

I want to find $x\in \ \mathbb{Q} $ such that the first ten digits of $ x \pi $ are 1.234567890. I tried: ...
1
vote
1answer
99 views

Wrong root when using numerical values

I have the following inequality: $$ \sqrt{\frac{a}{2x}}+ \frac{b}{1-\frac{a}{a+\sqrt{a(2bx + a)}}} + \frac{a}{2x\frac{a}{a+\sqrt{a(2bx + a)}}\left(1-\frac{a}{a+\sqrt{a(2bx + a)}}\right)} < f $$ on ...
0
votes
0answers
56 views

Workaround of non-integer indexed objects? [duplicate]

When using indexed object, I found the behavior of value 0.7 as the index quite strange, then did the following test. The first output cell was executed directly as the second input cell. Have not ...
4
votes
1answer
80 views

What is a sufficient decrease in the merit function?

As far as I understand, the merit function measures how far the data is from the fitted function. I am calulcating the second partial derivative of a function, and then numerically finding its maxima ...
8
votes
1answer
104 views

Abnormal behavior of RealDigits[x]

In the Details of the document of RealDigits writes the following line: RealDigits[x] normally returns a list of digits of ...
1
vote
1answer
73 views

Nonlinear 2nd order ODE with regular singularities

I am tring to solve the following ODE with NDsolve $2x~(1-x)~f''(x)+(3-4x)~f'(x)+a~f(x)+b~f^n(x)=0;~~a,b\in\mathbb{R},~n\in\mathbb{N}$. The mathematica "code" is: ...
1
vote
1answer
58 views

Behaviour of RealDigits expected or wrong?

Is this behavior expected or a bug? RealDigits[10304.390456] {{1, 0, 3, 0, 4, 3, 9, 0, 4, 5, 5, 9, 9, 9, 9, 9}, 5} when I ...
7
votes
2answers
208 views

NIntegrate fails to converge under almost any PrecisionGoal, MinRecursion etc. How can I trust the result?

I have been getting some ideas by reading other related questions in the forum, but the integral I have to do is not converging in many cases. The integrand is of the form: ...
0
votes
0answers
47 views

FindRoot precision with non-rationals [closed]

I have a function as shown below which always crosses zero just before 1. When I try to find the roots, it works fine most of the time but for some combinations, it gives the following error, even ...
0
votes
1answer
55 views

Problem with precision of fraction numbers

I have tried to take a series of harmonic numbers using Mathematica and its precision but there has been an issue. So far when I computed the sums at a whole numbers using a precision of 100 digits I ...
1
vote
0answers
69 views

Problem with calculating Harmonic Numbers

I have tried to take a series of Harmonic Numbers using mathematica but there have been issues in calculations. So far when I computed the sums at a small value range such as ...
1
vote
1answer
81 views

Limited Precision calculation in Mathematica

I apologize upfront for the simple minded question, however i couldn't find an answer in either the Mathematica documentation or Stack exchange. I am trying to explore the effect of finite precision ...
3
votes
1answer
67 views

WorkingPrecision in a sum

If I am interested in getting a fairly precise plot of f2 below, can I use WorkingPrecision to do this? ...
4
votes
1answer
41 views

Failure in use of SetPrecision with Filter

I am working with a narrow band filter and I wish to use a high precision version. The filter is defined using Integers with Laplace variable s. Here is the, rather horrific, equation: ...
1
vote
1answer
55 views

Invoking WorkingPrecision slows down Eigenvalue calculation drastically?

Normally, obtaining eigenvalues of random numerical matrices is fast. For instance a generic result looks like ...
1
vote
0answers
59 views

Odd plotting/math issue (could be a precision problem)

I've got a pretty odd error on a project I'm working on and was hoping to enlist some advice to fix it. The goal of this notebook is to show that I can eliminate the non-normalizable (blowing up part) ...
1
vote
1answer
62 views

Calculations after NumberForm [duplicate]

As specified in documentation center the functions AccountingForm, NumberForm, etc. are useful only to display numbers in ...
3
votes
1answer
55 views

Export followed by Import producing “0.e1” numbers

I had a large table of data that I exported, and then when it had completed, I exported it to a file. (Just in the form Export["filename.dat", data], no specified ...
1
vote
0answers
40 views

Using precision in Mathematica code [duplicate]

I would like to use a specific precision for several different calculations in Mathematica code. I know that using SetPrecision can give you the required precision ...
3
votes
0answers
98 views

Is FindRoot wrong about its WorkingPrecision?

I noticed an odd mismatch between the behaviors of NDSolve and FindRoot. If you give NDSolve an equation of a certain precision, say 20, and tell it to use a higher WorkingPrecision, say 30, it will ...
3
votes
1answer
122 views

How is Precision of Imported Data managed?

I am working on a financial/banking type application and part of the work is to import numeric data of 15 to 20 digits of precision. I am having trouble determining the best way this should be done. ...
12
votes
1answer
236 views

How to add AccuracyGoal and PrecisionGoal options in a numerical function?

There are many built-in functions that contain AccuracyGoal, PrecisionGoal and ...
3
votes
0answers
247 views

Precision and accuracy in NDSolve and NMinimize

I use NDSolve quite a lot and have noticed that setting values for AccuracyGoal and ...
5
votes
0answers
85 views

Is there a problem with some of the curated Star Data?

I'm not really sure if I'm doing something wrong, or if there's a problem with some of the Mathematica curated data on stars. My problem is this: I'm trying to find the location (latitude and ...
0
votes
1answer
53 views

If statement for evaluating small values

I have a simple calculation which I am trying to use if condition to evaluate summation of some values, here's a code; ...
5
votes
1answer
74 views

Can Someone Please Explain Internal`$SameQTolerance?

If I input Internal`$SameQTolerance (* output = 0.30103 *) which is the approximation of Log[10,2], or ...
2
votes
1answer
45 views

Integrate and NIntegrate combined, giving MaxPrecision error

I am trying to integrate the following : ...
0
votes
0answers
18 views

Increasing the zero threshold [duplicate]

I have a function similar to this: func[x_]:=Log[1+x] when I evaluate it at very small arguments, it will become 0, i.e. ...
4
votes
1answer
99 views

Inaccurate Heliocentric coordinates of PlanetaryMoonData

I have noticed that the heliocentric coordinates obtained with PlanetaryMoonData are very inaccurate. Fore example, consider the Galilean moons of Jupiter: ...
1
vote
1answer
183 views

Precision while calculating Fourier transform

I'm trying to understand how precision works in Mathematica. Particularly I'm calculating discrete Fourier transform using the Fourier function and calculating it ...
0
votes
0answers
63 views

CharacteristicPolynomial returns 0

I have a following matrix. ...
16
votes
0answers
215 views

Is MathieuC for moderately large imaginary arguments broken?

I'm trying to plot MathieuC[-3,0.3,I x] for $x\in[0,10]$, and here's what I get even with arbitrary precision arithmetic (here I use ...
0
votes
1answer
34 views

Precision digits in Log[] [duplicate]

Why does N[Log[10, 6613], 20] give the requested 20 digits of precision (* $3.8203985227039816648$ *) but ...