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0
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0answers
56 views

Small difference between large numbers [on hold]

I would like to calculate the difference of the two large numbers, which are close together. See here my (sorry, quite long) code: ...
5
votes
1answer
57 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
42 views

Integrate and NIntegrate combined, giving MaxPrecision error

I am trying to integrate the following : ...
0
votes
0answers
16 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. ...
2
votes
0answers
42 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
115 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
44 views

CharacteristicPolynomial returns 0

I have the following matrix. ...
16
votes
0answers
192 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
30 views

Precision digits in Log[] [duplicate]

Why does N[Log[10, 6613], 20] give the requested 20 digits of precision (* $3.8203985227039816648$ *) but ...
1
vote
1answer
36 views

Generation of list of values for small gap among values

I need to run a loop as Table[expr,{i,imin,imax,di}] where I want di to be as small as order of ...
4
votes
1answer
74 views

FindMinimum's WorkingPrecision behaviour

I discovered the following behaviour when using FindMinimum for constrained optimization: ...
0
votes
1answer
37 views

Fine precision control in IntervalSlider

I would like to develop a simple slider for exploring a wide range of intervals on the real line. Is it possible to get the MinimalSize of IntervalSlider to work ...
2
votes
2answers
155 views

How to get the digits after the decimal point

I have N[Sqrt[2], 8] which outputs 0.4142136 How do I get the 4142136 part out of it? I ...
0
votes
2answers
71 views

Why is Sin[2.0 Pi] = -2.44929 x 10^-16 and not 0.0?

Why does Sin[2.0 Pi] evaluate to -2.44929 x 10^-16 and not 0.0?
3
votes
0answers
59 views

WorkingPrecision in LogLogPlot creates wrong plots

I seem to have found a bug with LogLogPlot in version 10. If I specify a working precision, the function produces total garbage. Here is a simple example. The first case, without WorkingPrecision ...
2
votes
0answers
45 views

Precision loss in FourierDCT

I have high precision data that I want to do Fourier transform with, but it looks like the precision is lost dramatically. ...
-1
votes
1answer
76 views
1
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0answers
72 views

How to control precision of parameters in NonlinearModelFit?

I am using NonlinearModelFit for fitting a dataset to some complex numerical model function that depends on a few parameters. The final required precision of these parameters is very low, like 3 ...
3
votes
1answer
103 views

Precision of NIntegrate

At the moment I am considering a "difficult", highly-oscillatory integral in Mathematica. It calculates the integral without any complaints. However, I am also trying out a numerical method with which ...
6
votes
1answer
128 views

Numerical Integration different in Mathematica version 9 and 10 with same options

I have noted that the same function with the same settings gives me different results in Mathematica version 9 and 10. This involves integrating numerically interpolating functions and so on. Here a ...
1
vote
3answers
97 views

NSolve & PrecisionGoal

I am using NSolve to find numerical solutions of a particular equation. I do not need the solutions to as high of a precision as the other numbers in my notebook. To improve run time (I am iterating ...
0
votes
1answer
61 views

Accuracy and WorkingPrecision

Observe that ...
1
vote
1answer
78 views

Wrong generalized eigenvalues of large numeric matrices

I've been working on a toy model of a variational method of a Hamiltonian H with an overlap matrix S. The point is that when H and S are small enough, Mathematica gives the correct eigenvalues (≈ ...
0
votes
0answers
22 views

why i cannot get appropriate number with my custom precision? [duplicate]

why i cannot get appropriate number with my custom precision? In[25]:= N[(1 + Exp[-30])/(1 + Exp[-29.9]), 1000] Out[25]= 1. I expect to see a few digits after ...
2
votes
2answers
183 views

Permanently rounding numbers/values to a given number of significant figures

I am searching for a simple way of rounding and setting an input to a desired number of significant figures. There are a vast number of posts that discuss similar problems, but none address this ...
4
votes
1answer
112 views

Is the divergence between Round and setting an explicit precision intentional or a bug?

Introductory remark: I take it (from Mathematica's online documentation), that Precision is effectively the number of significant digits, as seen by the system. ...
3
votes
1answer
39 views

Is it possible to generate a message when precision upgrade occur?

I use Mathematica mostly for numerical simulation, so most of the time double precision (or machine precision) is enough for me. Mathematica has this nice feature of automatically upgrade to arbitrary ...
0
votes
0answers
36 views

Failed to use SetPrecision

I am calculating the below formula: $$ \text{ER2}(\alpha,\text{K},\text{q})\text{:=}1+\sum _{m=0}^{K-1} \binom{K+\alpha }{m} \sum _{r=0}^m \frac{(-1)^r \binom{m}{r}}{\left(\frac{1}{q}\right)^{\alpha ...
0
votes
1answer
84 views

Why is chop being ignored? [closed]

If I use Chop[10^-4, 10^-3] then I'd expect the output to be zero. However, this is not the case. There is of course a very easy workaround since I can define ...
3
votes
2answers
153 views

Explicit digit-count (precision) of real number

I'm trying to do something which seems like it should be simpler than it is (at least in my attempts at it). I have some code where I read in a list of numbers generated for me by a coworker. These ...
1
vote
1answer
95 views

Option: number of digits

The command NestList[Cos, 1.5, 10] produces the list: ...
5
votes
0answers
44 views

Change system options in package

I use Mathematica mostly for numerical calculations, and sometimes the performance of numerical calculations can be greatly improved if the high-precision arithmetic can be switched off by ...
0
votes
0answers
46 views

Why does Save change my data precision?

I have some data from some Mathematica program, and it appears that the precision of the data has been slightly changes when I save the data and reload it again. ...
0
votes
0answers
64 views

universal precision control in Mathematica

There are many ways to control precision in Mathematica, such as PrecisionGoal in specific build-in commmands or SetPrecision to some variables. I got two questions below, (1) If I do not set any ...
1
vote
0answers
44 views

Which operations preserve digit precision?

Imagine I had to use numbers with a 600 precision digits. Do all mathematical operations, like +,-,...
5
votes
0answers
55 views

The change of precision doesn't work in ParallelDo. Is it a bug in Parallel?

Cross-post: http://zhidao.baidu.com/question/2075301703219376588.html Input: ...
3
votes
1answer
66 views

Is it possible to change the MinPrecision in command “Compile”?

I'm using "Compile" to do some numerical calculation and I need high Precision. I was wondering if it is possible to change the Precision in command "Compile" to some $MinPrecision?
0
votes
1answer
65 views

Fourier and InverseFourier precision [duplicate]

I'm quite puzzled by Mathematica lack of precision with Fourier and InverseFourier. I tried the following code ...
3
votes
1answer
46 views

Deferent results depending on the input form of the matrix [closed]

Why is it so, N[Eigenvectors[{{1., 0.5, 4.}, {2., 1., 2.}, {0.25, 0.5, 1.}}]] returns: ...
1
vote
1answer
65 views

How to show right count of decimal number in mathematica 10

I have some random number x. It can be 222.1245646 or 3.141562652. How should I show this number to 5 decimal numbers ? I cant use this: N[x, 5] because it shows 5 ...
1
vote
2answers
74 views

ListPlot3D with small (but acceptable) precision

Consider the following minimal example: ...
1
vote
1answer
81 views

Increase Precision in Numerical Integration

I need to generate a table of Chebyshev expansion coefficients of trigonometric functions (in this case Cos[2 Pi t] to very high accuracy. Code is: ...
0
votes
0answers
44 views

How to set all the numerical values as double

Is it possible to set the accuracy of every numerical value and the result of every computation to double like in Matlab? I want Mathematica to use just 3 or 4 ...
0
votes
3answers
116 views

High-Precision NSolve

I need to calculate the intersection of two curves f1[x_] := ((Zl ρ ) Exp[-x]) f2[x_] := (α k e^2 /x^2) Where ...
2
votes
1answer
88 views

Working precision and pure functions in FindMinimum

I have this function: fun = (# - 5.0)^2.0 & Then, I want to find the minimum: ...
0
votes
1answer
129 views

How to work with decimals (e.g. 0.95) instead of fractions (95/100) and get the same result

In my code I have a function, F, that depends on several parameters, say a,b,c: F(a,b,c). I need to give a grid of values to a,b and c to obtain the value of F. My grid of values are decimal ...
1
vote
0answers
59 views

the default option of NDSolve

How should I find out what the default value of Accuracy and Precision is in the NDSolve? I have a pde that when I asked it to solve for me the equation with a special Accuracy and precision it gave ...
3
votes
2answers
214 views

Increase precision for a entire notebook

I am quite a newbie and it is taking me so much time to understand what I need to do to achieve something really simple and I still haven't found it. I run a dynamic model of a metabolic pathway in ...
2
votes
1answer
65 views

Range and decimal digits [duplicate]

When I set Plot[Sin[x], {x, -2, -1}, Frame -> True, Axes -> False, FrameTicks -> {{Automatic, Automatic}, {Range[-2, -1, 0.2], Automatic}}] I ...