# Tagged Questions

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

282 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 ...
109 views

### Option: number of digits

The command NestList[Cos, 1.5, 10] produces the list: ...
85 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 ...
48 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. ...
130 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 ...
51 views

### Which operations preserve digit precision?

Imagine I had to use numbers with a 600 precision digits. Do all mathematical operations, like +,-,...
68 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: ...
175 views

### Is it possible to change the precision in 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 ...
85 views

### Fourier and InverseFourier precision [duplicate]

I'm quite puzzled by Mathematica lack of precision with Fourier and InverseFourier. I tried the following code ...
65 views

### Deferent results depending on the input form of the matrix [duplicate]

Why is it so, N[Eigenvectors[{{1., 0.5, 4.}, {2., 1., 2.}, {0.25, 0.5, 1.}}]] returns: ...
130 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 ...
79 views

### ListPlot3D with small (but acceptable) precision

Consider the following minimal example: ...
178 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: ...
397 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 ...
161 views

### Changing working precision to 10 in NIntegrate introducing error messages and giving bigger error than precision 5

I have two numerical integrals as follows: ...
380 views

### Working precision and pure functions in FindMinimum

I have this function: fun = (# - 5.0)^2.0 & Then, I want to find the minimum: ...
245 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 numbers....
162 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 ...
583 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 ...
81 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 ...
42 views

### Numerical Error with Matrix operations [duplicate]

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 ...
510 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 ...
183 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 $x$. ...
249 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 ...
254 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 ...
80 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: ...
553 views

If I change $MinPrecision before running ListPlot[{{1, 2}}], there will be a warning in Mathematica 10. But there is no warning ... 2answers 547 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 ... 2answers 241 views ### Why does N[Re@f] give complex result? Consider this code: ... 1answer 223 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. ... 0answers 129 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 ... 0answers 66 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 ... 1answer 80 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 ... 2answers 118 views ### SetPrecision — different values subtracted from unity gives same value How are my results possible? CODE: SetPrecision[FibersFailedNew, 40] 3.612171938234261799295174910010284760488*10^-16 <... 1answer 146 views ### plot totally fragmented, WorkingPrecision,matlab comparison I am trying to plot ... 1answer 85 views ### Inaccuracy of Piecewise function? [duplicate] I have the following issue and can't find a solution so far. ... 3answers 315 views ### Why does this Quantity calculation lose precision? ... 0answers 157 views ### Meaning of backtick in conjunction with units [duplicate] In this fragment from an equation solution the backtick is used twice: ... 2answers 191 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, ... 1answer 461 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 ... 0answers 30 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 ...
322 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 ...
108 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, ...
312 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. ...
251 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 ...
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 ...
750 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 ...
331 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 ...