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0
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0answers
37 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
310 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
158 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
206 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
157 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
65 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: ...
1
vote
1answer
178 views

How to suppress a warning message

If I change $MinPrecision before running ListPlot[{{1, 2}}], there will be a warning in Mathematica 10. But there is no warning ...
4
votes
3answers
256 views

Importing High Precision (22 digits) data from a file

I want to import list from a file and I am using ReadList but my data is in format like this 8.2457409790900004e+08 but it i being imported like $8.24574*10^8$. Is ...
4
votes
2answers
198 views

Why does N[Re@f] give complex result?

Consider this code: ...
6
votes
1answer
173 views

Numerical error in Mathieu functions

Consider the MathieuCharacteristicA function, which is a piecewise function according to the documentation. The discontinuity happens at integer number. ...
4
votes
0answers
108 views

Precision problem while evaluating RegionMember or Element in V10

I'll try to give you a background on where the problem occured. The problem itself is defined near the end of the post. I'm running a sort of a simulation of a particle in a box. I finally got my ...
1
vote
0answers
58 views

Precision of sliders in WebMathemtica

I have been developing a manipulate plot to put on the web. One of my parameters varies over a small interval, {{D32, 2.38*10^-3, "D32"}, 0.001227, 0.0049108}. This ...
1
vote
1answer
59 views

How to make a discretized NMinimize more precise

I am using Mathematica for physics research and I want to minimize a Hamiltonian equation with respect to two variables (I have also discretized the problem). I have a single constraint. When I plot ...
1
vote
2answers
97 views

SetPrecision — different values subtracted from unity gives same value

How are my results possible? CODE: SetPrecision[FibersFailedNew, 40] 3.612171938234261799295174910010284760488*10^-16 ...
1
vote
1answer
123 views
1
vote
1answer
72 views

Inaccuracy of Piecewise function? [duplicate]

I have the following issue and can't find a solution so far. ...
6
votes
3answers
268 views
0
votes
0answers
107 views

Meaning of backtick in conjunction with units [duplicate]

In this fragment from an equation solution the backtick is used twice: ...
2
votes
2answers
155 views

NIntegrate - WorkingPrecision

I am trying to NIntegrate this expression. It is very close to zero, and so gives all possible types of errors. More precisely, ...
0
votes
1answer
276 views

How to get more accurate orthonormal eigenvectors?

I have a matrix M with real entries in MachinePrecision. I compute its eigenvectors and construct matrix ...
1
vote
0answers
27 views

Ignore $MinPrecision when using Print

I have a function that contains a For loop and sometimes takes several hours to run. It's important that I keep a high precision, and I insert ...
1
vote
1answer
224 views

Numerical Instability?

Current Status Please skip ahead to Update 2: the key questions are now: 1/ Why does Mma generally fail to find the minimum for a well behaved function when the function does not have infinite ...
1
vote
1answer
68 views

ReadList error with negative very small numbers

When I try to import data with ReadList from a file containing very small numbers (~10^-318), positive data is handled well, ...
4
votes
3answers
227 views

Increasing the precision of a calculation

Clearly I have misunderstood how to do this: I seem unable to understand how to get more digits out of a calculation and I can't see why - the following piece of code illustrates the issue. ...
0
votes
1answer
148 views

How can I obtain more significant digits? [duplicate]

I type f1[x_] := 12 x^5 - 975 x^4 + 28000 x^3 - 345000 x^2 + 1800000 x N[f1[15.5], 15] and obtain 3.74112*10^6 BUT It´s not true!!! the result is larger than ...
1
vote
0answers
34 views

Frontend displays wrong number digits [duplicate]

How do I change the default precision in Mathematica? Somehow the setting has been changed to 1 digit, so if I type Timing[...] I get {1., ...} which is ...
8
votes
2answers
697 views

Finding differences between Pi with varying number of decimals

I have the following code In[32]:= N[Pi, 2] Out[32]= 3.1 In[33]:= N[Pi, 1] Out[33]= 3. In[34]:= N[Pi, 2] - N[Pi, 1] Out[34]= 0.*10^-1 Why can't Mathematica ...
3
votes
1answer
196 views

Fixed-Point Numbers in Mathematica

I am working with a library that needs input in a Fixed Point notation. I’d like to figure out a way to convert the floating point results into fixed point representation. The fixed point length is ...
1
vote
1answer
752 views

Plot periodic function from Dirac delta function [duplicate]

Sorry for my bad english. I need to plot periodic function from dirac delta: δT(t)=∑δ(t–n*T), where T - is a constant, and n=-20..20 And after them, plot new function fd=f(t)*δT(t) - discrete signal ...
5
votes
1answer
60 views

Mysterious behavior of Precision for complex arrays

Mysterious behavior of Precision: {{1.0+I*0.0},{0.0+I*0.0}} // SetPrecision[#,30]& // Precision // Print; ...
4
votes
1answer
107 views

Issues with $MachineEpsilon

I'm attempting to add $MachineEpsilon to numbers I am pulling from the domains of 3 interpolating functions. I pulled 3 numbers, and for one of these numbers adding ...
3
votes
0answers
107 views

Tools for Stability/Automatic Error Analysis in Mathematica

I have a longer analytic expression in several variables containing special functions and others. Does Mathematica bring tools - or are there any packages - to examine the stability when I evaluate ...
1
vote
1answer
188 views

ListPlot with high precision

I have a list of numbers, e.g. {{1.,0``27.698970004336022},{2.,0``27.698970004336015}} but usually much longer, suitable for ...
2
votes
0answers
144 views

how to calculate with just double floating point precision [duplicate]

I want to calculate with simple double floating point precision. ...
3
votes
4answers
196 views

AccountingForm w/o significant figures

Basically I want to build a chart like something I would do in Excel. It should look like this: Here is the formula I'm using and what I've done so far ...
6
votes
2answers
2k views

How to convert a string of number into real numbers without precision loss

I searched and did not find similar answers which can resolve the 'no precision loss' issue. A sample string is: ...
4
votes
1answer
1k views

How to set the working precision globally? $MinPrecision does not work

I want to increase the precision globally to 50 at least, but $MinPrecision does not work. ...
0
votes
1answer
101 views

Truncate a fractional value to particular number of bits?

If I have a fractional value, how can I truncate (not round) that to a certain number of bits, like 8? For example, for Pi 3.141569265359... the fractional part is 0.141569265359... ...
5
votes
1answer
576 views

ReadList can't read from file containing high-precision Reals

I want to read a file which contains seven columns of real numbers. Mathematica seems to have a problem with the high precision I need. My code: ...
2
votes
1answer
129 views

Why the EuclideanDistance of these 2 exact points generates the warning N::meprec?

The two points are: pts = {{1/4 (-1 - Sqrt[5]), Sqrt[5/8 - Sqrt[5]/8]}, {1/4 (-1 - Sqrt[5]), -Sqrt[5/8 - Sqrt[5]/8]}}; EuclideanDistance @@ pts ...
7
votes
0answers
71 views

Is there a way to get BSplineFunction beyond MachinePrecision?

I have been using BSplineFunction (Mathematica 8) to generate a smooth representation of some data, which I might then do some further processing on. As I ...
13
votes
2answers
376 views

Why do NumberForm and Round apparently use different tie-breaking methods?

When rounding numbers (for example, rounding a real number to the nearest integer), the "round to nearest" rule is usually used. For example, 1.4 is rounded down to 1 and 1.6 is rounded up to 2. ...
45
votes
2answers
2k views

When I can assume that all decimal digits returned by Mathematica are provably correct?

How to Control the Precision and Accuracy of Numerical Results Arbitrary-Precision Numbers Mathematica works with exact numbers and with two different types of approximate numbers: ...
1
vote
1answer
141 views

Working precision for each variable

How can I define working precision for each variable individually for example: Maximize[x y< 100, {x, y}] where the working precisions for ...
6
votes
2answers
152 views

Large Number times Tiny Number

A (maybe noob) question: Let a = 1234567891234567889998.5 b = 1234567891234567889999.5 Mathematica (v8) yields for ...
1
vote
1answer
229 views

Output precision

I've solved some equations using FindRoot and then computed some values. Now when I print the output, I only get a certain precision {{0.01, 496.983, 61.3147, ...
0
votes
2answers
362 views

Problem with working precision

I have tried to resolve the problem of the following link How can I solve precision problem I can tell the problem described in that link shortly here, It's no mater how many precision is there after ...
0
votes
0answers
28 views

What is the precision of this number? [duplicate]

In a matrix evaluation, I got the following number. 2.8330574963868513` I understand that the number after ` shows the precision of the output number. But this ...
4
votes
1answer
168 views

Padding plot ticks with zeros on the right

I would like to know how can I make a real-valued plot tick pad with a zero to the right of the decimal point on integer values. This is what I have: ...
3
votes
1answer
254 views

Numerical Error with Large Matrices

I am writing a Finite Element Analysis program in Mathematica. The code involves handling a large matrix with large entries. I get an error when I try to use Mathematica's "LinearSolve" to solve a ...