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2
votes
1answer
43 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
57 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 ...
0
votes
0answers
21 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 ...
2
votes
2answers
82 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
51 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
31 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 ...
4
votes
2answers
167 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
121 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
171 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
101 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
55 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
69 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
131 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
181 views

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

Consider this code: ...
5
votes
1answer
114 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. ...
3
votes
0answers
81 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 ...
0
votes
0answers
50 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
50 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
75 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
100 views
1
vote
1answer
60 views

Inaccuracy of Piecewise function? [duplicate]

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

Meaning of backtick in conjunction with units [duplicate]

In this fragment from an equation solution the backtick is used twice: ...
2
votes
2answers
123 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
151 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 ...
0
votes
0answers
22 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 ...
0
votes
0answers
28 views

How to get precision for a small calculation? [duplicate]

For pc1 and pc2 this gives the answer to only four decimal places. How can I get better precision? ...
1
vote
1answer
156 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
50 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
173 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
105 views

How can I obtain more significant digits? [closed]

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
32 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 ...
1
vote
1answer
183 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
55 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
86 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
87 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
132 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
106 views

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

I want to calculate with simple double floating point precision. ...
3
votes
4answers
160 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 ...
5
votes
2answers
960 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
562 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
87 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
425 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
105 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 ...
6
votes
0answers
58 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 ...
12
votes
2answers
284 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. ...
44
votes
3answers
1k 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
123 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
145 views

Large Number times Tiny Number

A (maybe noob) question: Let a = 1234567891234567889998.5 b = 1234567891234567889999.5 Mathematica (v8) yields for ...