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0
votes
0answers
40 views

CharacteristicPolynomial returns 0

I have the following matrix. ...
0
votes
0answers
29 views

Set precision on output dataset [closed]

How do I set the output precision such that if a value is calculated to be e.g. 9.7942*10^-18, Mathematica doesn't output that value, but it just outputs $0$ instead. I tried ...
16
votes
0answers
173 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
27 views

Precision digits in Log[] [duplicate]

Why does N[Log[10, 6613], 20] give the requested 20 digits of precision (* $3.8203985227039816648$ *) but ...
4
votes
1answer
63 views

FindMinimum's WorkingPrecision behaviour

I discovered the following behaviour when using FindMinimum for constrained optimization: ...
0
votes
1answer
33 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
148 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
68 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
56 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
43 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
66 views
0
votes
0answers
59 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
95 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
122 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
95 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
55 views

Accuracy and WorkingPrecision

Observe that ...
1
vote
1answer
72 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
154 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
103 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
38 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
80 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
144 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
91 views

Option: number of digits

The command NestList[Cos, 1.5, 10] produces the list: ...
5
votes
0answers
43 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
45 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
61 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
43 views

Which operations preserve digit precision?

Imagine I had to use numbers with a 600 precision digits. Do all mathematical operations, like +,-,...
4
votes
0answers
51 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
61 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
62 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
64 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
73 views

ListPlot3D with small (but acceptable) precision

Consider the following minimal example: ...
1
vote
1answer
77 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
43 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
104 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
78 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
119 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
54 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
187 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
61 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 ...
0
votes
0answers
36 views

Numerical Error with Matrix operations

A is a 3x3 matrix, b is a 3x1 vector. I try to convert [A|b], a 3x4 matrix, to [I|0]. So the formula is right multiple ...
6
votes
2answers
297 views

A problem about fixed point iteration theory

Description Recently, I have been learning a couse called "Numerical Analysis". The fixed point iteration theory was introducted to solve the ...
2
votes
4answers
153 views

Precision problem with numerical solution of a differential equation

I want solve $$ 2\sqrt{|\gamma|}x = \int_{1}^{t} dy \sqrt{\frac{1+2|\gamma_2|y}{y^2(1-y)}} $$ where $0<t\leq $1. I'm using a for cycle to evaluate t, calculate the integral and the assign the $x$. ...
8
votes
2answers
204 views

Error computing sum of sum of digits

I've defined a function that computes the sum of the base-b digits of n: DigitSum[n_, b_] := Total[IntegerDigits[n, b]] Then I defined a function that computes ...
1
vote
1answer
149 views

NDSolve fails for certain choices of parameters and solve range

I'm trying to solve a pair of coupled ODEs with NDSolve. I know roughly what the solution should look like (both should give periodic functions, pi/2 out of phase, the amplitude of which damp towards ...
4
votes
2answers
64 views

numerical precision in output file

I want to write the numerical results of a computation to a file which is to be read in Fortran. The data looks like: ...