Questions tagged [machine-precision]
For questions on the use of machine-precision real numbers (also known as floats), the numbers that can be directly manipulated through the underlying numerical capabilities of your computer system.
229
questions
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42
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141
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Preventing Mathematica from considering small values to be equal to zero [duplicate]
In my calculations I have a variable (say z) which can be an argument of Log, say, z Log[z]. ...
- 629
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votes
1
answer
77
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ContourPlot showing breaks in contours
I'm trying find graphically the solutions of the intersection of the following functions.
...
- 573
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1
answer
62
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How to get the correct result in a simple operation in Mathematica
I have the following values for x[[i]], y[[i]] and A[[i,j]]:
...
- 45
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votes
2
answers
77
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NIntegrate numerical accuracy and errors
I have the following 3x3 matrix
M = {{-I*ω + Γ/2, I*g1,
0}, {I*g1, -I*ω + κ1/2, I*g2}, {0,
I*g2, -I*ω + κ2/2}};
Finding the eigenvalues and eigenvectors
...
- 385
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1
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135
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How to use a higher precision?
Below is my code. If I set W to $10^{55}$, it breaks down and the result is wrong. What do I need to do to use W as large as $10^{200}$?
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- 123
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1
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272
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How to improve the performance of this code
I have implemented a code in Mathematica 9 to simulate a scattering problem, and I got really disappointed about its performance when compared to Matlab. Since I am a newbie in Mathematica, would ...
- 1
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0
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84
views
How to set the precision for the entire notebook
I want to do various computations conditional on a given precision for the entire notebook. I use the following code:
...
- 5,490
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1
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81
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When does arithmetic with approximate numbers not follow basic properties? [closed]
Consider this:
x = Exp[3.5*^15]
(* OVerflow[] *)
The above is well documented and so is the next result.
...
- 884
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0
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54
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Overflow + Underflow Problems with Code
I am trying to use Mathematica to verify simulation results with an analytic result.
The analytic results are performance measures of the M/D/1 queue, which unfortunately uses
the factorial function ...
- 427
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0
answers
59
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How to set up precision by default?
I have a table computing many numbers with large precision. Because of this, probably, Mathematica consumes a lot of RAM. Is it possible to restrict the precision in any calculations by default (...
- 4,652
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42
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Why is the `N` function giving me the wrong result when using WolframScript? [duplicate]
I am using wolframscript.exe to learn mathematica and I would expect the following code to return 0.7071:
...
- 185
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63
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Mathematica accuracy errors when creating data
I created training data for a neural network and below are two errors I got
The only code that uses "FindRoot" command is the following
...
- 295
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41
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General::munfl - Precision lost in LinearModelFit
I am new to mathematica so I am confused regarding the loss of precision in LinearModelFit. In building a linear model with uora (1 or 2) and encodeSeverity (1,2 or 3)
...
0
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0
answers
52
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Solving a determinant to get non-zero roots in a heat transfer problem
I am trying to solve a mathematical model of a heat transfer problem.
As an intermediate step there is a characteristic equation in the form of a determinant, which needs to be solved for variable <...
- 297
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votes
0
answers
92
views
How to change Machine Precision digits to meet the tolerances
I am trying to solve for Tcm and Mag by solving nonlinear equations using FindRoot command using following code:
...
- 51
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0
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71
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Problem with the Rank of a matrix after a FindRoot
I am solving a boundary problem defined by a set of four-component vectorial functions. Without going into many details, I have two functions on the left and two on the right of an interface. The ...
- 121
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0
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101
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How to copy and paste numbers with "`" mark and use them in calculations, without using N or setting precision every time
Suppose we have run a calculation and get a number like
2.758952615889003`
If we then copy-paste this number and do a calculation like
...
- 789
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28
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Different sensitivies from LinearSolve and Eigenvalues. How to conciliate them?
I use the following functions to receive a matrix, and make it symmetric positive definite:
...
- 2,517
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95
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Understanding Working Precision - two example equations
I am trying to understand how WorkingPrecision works, and in general how very small/large numbers are to be handled.
Let me preface I probably do not have ...
- 755
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0
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20
views
Conflicting output provided by `N[...]`
I am trying to evaluate an expression :
(-((I (k2 - k1) (-1 + E^(2 I (k2 - k1) \[Pi])))/(-1 + (k2 -
k1)^2))) /. {k1 -> 2, k2 -> 7}
This gives ...
- 431
0
votes
0
answers
352
views
Dealing with General::munfl errors
Edit: So, while trying to figure out a minimal exmaple, I found out that my main problem was actually unrelated to this and it just happened to be that giant pile of warnings and error messages coming ...
- 21
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0
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72
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How to resolve underflow occurrences?
I am solving a second order differential equation described by odey below. For the asymptotics, I have the following code which will be used as initial conditions for NDSolve.
...
- 181
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0
answers
331
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Plot a function with very small values, close to zero
I want to plot a function with very small values, close to zero, but even though the limit is -3/2 as x->0, I can't get any ...
- 569
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0
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104
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Getting max precision limit overflow for a very simple calculation
I've never seen this error on such a simple calculation.
Does anybody know how to fix this annoying error?
user58873
0
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64
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ListLinePlot gives the correct values but N doesn't
I have solved a set of 6 differential equations with DSolve. When I use the table command and produce the results of one of the equations given by DSolve, the ListLinePlot command gives me the correct ...
- 1,243
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44
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Unpredictable behavior of numerical error
A comparison of float calculation and exact expression for
NumberForm[0.3^2 - (3/10)^2, 18]
gives an exact zero for $0.3$.
However,
...
- 1,567
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1
answer
90
views
Unexpected behavior of subtraction with approximate numbers [duplicate]
I'm using the Table command to generate a list of values:
FullForm /@ Table[10. - x, {x, 2.7, 2.8, .1}]
and I get the ...
- 1
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0
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70
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