Questions tagged [precision-and-accuracy]
The precision-and-accuracy tag has no usage guidance.
571
questions
9
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answer
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IntegerPart - is this a known bug?
I'm working in Mathematica 13.0 and I type
a=0.00001;
IntegerPart[a/a]
and well, the output is 0.
Try with almost any other value of ...
1
vote
0
answers
32
views
Discrepancies in NDSolve Solution Between 4D and its Reduced 3D Counterpart
I have two systems, a 4D system and a 3D system. The 3D system is a reduction of the 4D system in such a way that:
...
- 419
5
votes
1
answer
101
views
Mathematica ignores precision requirement when evaluating a Legendre function
Bug persisting through 13.1.0 [CASE:4953269]
When attempting to calculate a certain associated Legendre polynomial within a given precision, Mathematica seems to ignore it if the argument is ...
- 1,217
0
votes
1
answer
53
views
How to improve the accuracy of integration with Bessel function without significant drop in performance?
Consider the following function and integral:
...
- 4,038
4
votes
2
answers
130
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Adding numbers with defined precision produces incorrect result
I've tracked a bug in my code down to the problem of adding two numbers together, with the left argument having machine precision, e.g by 3` . The issue is, if ...
- 557
0
votes
0
answers
31
views
What does standard deviation mean when using Predict[]?
I am using the Machine Learning function Predict[data, Method -> "DecisionTree"], and I am trying to get the most accurate measurement of its accuracy. ...
- 125
0
votes
2
answers
172
views
Why this integral gives zero?
I would like to compute this integral for a =100, ... ,1500
$$ \int_1^\infty \dfrac{\left(x^2-1\right)^{3/2}}{x} \,e^{-ax}\, dx $$
...
- 621
1
vote
0
answers
51
views
Controlling accuracy for code
So I have a lot of trouble controlling precision and or accuracy with Mathematica. I have tried reading up for it but in the end I get even more confused. Here is my code, it is a little long but it ...
- 635
4
votes
1
answer
239
views
NIntegrate fails to converge to desired accuracy
I am calculating an integral with Mathematica. This is the code I am using:
...
- 51
0
votes
0
answers
22
views
Issues with ConvexOptimization and SetPrecision
I am completely new to Mathematica (second day), so do not expect things to look polished.
I am trying to perform a ConvexOptimization over a List/Array (dimensionality ...
- 113
1
vote
2
answers
78
views
Plotting high precision high degree polynomial
When I plot a high degree polynomial such as (available as CloudObject since it is too big to explicitly include):
...
- 3,613
1
vote
1
answer
82
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Divide by zero warning: Actual division by zero or spurious?
I have the following code that calculates the gain of an amplifier
...
- 345
2
votes
2
answers
267
views
Error "is too small to represent as a normalized machine number; precision \ may be lost " for small values in Plot
I'm trying to plot two curves but I'm having issues with the lower end of the range:
...
- 1,252
3
votes
0
answers
62
views
What's the best method to use when NIntegrating a sinx + cosx type function?
I'm having some problems when trying to NIntegrate a sinx + cosx type function. I have already tryed several combinations of ...
0
votes
1
answer
69
views
Confusion about precision [duplicate]
When I evaluate
x = 1.0000000000000000001 (* Precision of 20 digits *)
Mathematica returns
...
- 1,032
-3
votes
1
answer
90
views
long division acurate answer on dividing long numbers [closed]
ok but first of all if i have the huge number to be divided what will i have to use for the division to be accurate long division or some other formula square root or 2 this is to calculate music ...
4
votes
1
answer
341
views
Real number equality (==) not working: what's the least-overcomplicated solution?
I'm running a program that evaluates equalities after I substitute all symbols for numbers. The equalities on floats are giving me trouble. My program is reaching a point where something like the ...
- 558
0
votes
0
answers
39
views
How do change precision in coefficients in matrices
I alway have this kind of matrices...
obviously I would like to have 0s instead of 10^-15. I've tried with N[] function but doesn't work. Does anybody know how to proceed in this case?
- 199
1
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3
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117
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Is the result given by NSolve sufficiently reliable to claim that there is such a solution for the equation?
I use this code for ContourPlot
...
- 463
0
votes
0
answers
35
views
How to obtain the most accurate maximum value of the given equation? Changing WorkingPrecision gives different results
I have two functions $ f(x,y) $ and $ g(x,y) $ over the domains $ 1.56 <x< 1.6$ and $3<y<\pi$.
...
- 463
0
votes
0
answers
32
views
Which result is more reliable in NMaximize in the given code? with `WorkingPrecision` or without it?
I have two functions $ f(x,y) $ and $ g(x,y) $ over the domains $ 1<x< 2$ and $0<y<\pi$. I use ContourPlot to ses those values of $(x,y)$ for which $g(...
- 463
0
votes
2
answers
113
views
How to calculate the maximum value of $x $ which satisfy the conditions $g(x,y)=0$ and $f(x,y)>1$?
I have two functions $ f(x,y) $ and $ g(x,y) $ over the domains $ 1<x< 2$ and $0<y<\pi$. I use ContourPlot to ses those values of $(x,y)$ for which $g(...
- 463
1
vote
2
answers
94
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NSolve and FindRoot give a value which is not correct; how can I obtain the exact solution of the given equation? [closed]
I have two functions $ f(x,y) $ and $ g(x,y) $, I use this code
...
- 463
0
votes
0
answers
73
views
Crashing mathematica 12.3 with a simple ODE
I'm trying to solve an ODE using the following code:
...
0
votes
1
answer
85
views
RegionMember command alternative that can check members exactly?
My problem is as follows:
I have an exact rational polygon created using ConvexHullMesh and given a rational point I need Mathematica to decide exactly if it is ...
- 635
2
votes
2
answers
99
views
1
vote
0
answers
54
views
Accuracy issue in computing a Markov Transition Matrix
this question is based on a previous post of mine. I am simulating a one-dimensional Markov process on a linear graph. Transition probabilities are different than zero only for nearest neighbours of ...
- 737
1
vote
1
answer
98
views
0
votes
0
answers
45
views
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 (...
- 4,038
1
vote
1
answer
93
views
How to make Mathematica work only with 10 digits? [duplicate]
I have a quite frustrating problem.
In my code, I need Mathematica to ignore everything after 10 digits.
For example I need it to treat:
25.26011447795545 as ...
- 635
1
vote
1
answer
51
views
2
votes
0
answers
85
views
Rational numbers in NDSolve
Is it possible to use NDSolve with Rational numbers instead of Real?
I use all rational ...
- 121
3
votes
1
answer
65
views
Which one is more accurate Solve or NSolve? How can I get the same result as Solve using NSolve in the given code?
I am using this code to calculate the quantity $sol$. Using Solve, I get the result $9.8598$
...
- 463
6
votes
2
answers
674
views
How to force Mathematica to do infinite-precision calculations?
Consider the following calculation:
1234*5678*90.12
The result is:
6.31439*10^8
However, I want to get a precise result. Of ...
- 145
2
votes
0
answers
36
views
Precision Issue in LinearOptimization - dual solution is not feasible
Trying to solve a linear program with high precision requirements and am interested in both the primal and the dual solution. Prefer solving the primal problem for convenience and solving the dual ...
- 471
4
votes
1
answer
71
views
Avoid Extrapolation When Using NMaximize on Interpolating Functions
I want to use NMaximize to find the maximum value given by one interpolation function with respect to a constraint given by a second interpolation function. The main problem is that NMaximize produces ...
- 179
1
vote
0
answers
24
views
Mathematica 12.1: Evaluation result does not show decimals [duplicate]
It surprises me that Mathematica does not show decimals after evaluating the following calculations:
500000+5.05
Result: 500005.
Expecting: 500005.05
...
- 493
1
vote
1
answer
109
views
Nonlinear model fit gaussian precision
I wanted to fit double gaussian but it doesn't work, it doesn't fit gaussian. The error I get:
Data:data Here is code
...
1
vote
2
answers
45
views
`KernelMixtureDistribution` error message about precision
I want to use KernelMixtureDistribution to deal with a large amount of data points. For example, the following codes shows how I use it:
...
- 463
0
votes
0
answers
42
views
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
0
votes
1
answer
52
views
Why it remains only one digit after point in this numerical computation?
Why? And why N doesn't help?
How to change and/or make it permanent?
- 725
2
votes
1
answer
59
views
"Sparse" Overflow error in NIntegrate
I want to evalutate an integral
$$I = \int_{-0.01}^0 \int_{-0.01}^0 \left(\frac{1}{\sinh|t_2+t_1+T| \sinh|t_2+t_1|}\right)^{2/m} \left(\frac{\sinh|2t_1+t_2+T|}{\sinh|t_1+T|}\right)^{1/m} \left(\frac{\...
- 923
0
votes
1
answer
46
views
NIntegrate::zeroregion error outside the integration domain
I am trying to integrate a function
$$\int_R \frac{1}{(\sinh|T-t_1+t_2|)^{\frac2m} (\sinh|t_1-t_2|)^{\frac2m}} \left(\frac{\sinh|t_2|}{\sinh|t_1|}\right)^{\frac1m} \left(\frac{\sinh|T-2t_1+t_2|}{\sinh|...
- 923
1
vote
1
answer
74
views
Wrong limit appears [closed]
Consider the following limit
$$
\lim_{x\to-\infty}x-\sqrt{x^2+7x}
$$
Going through some algebra leads to
$$\begin{align}
\lim_{x\to-\infty}x-\sqrt{x^2+7x}&=\lim_{x\to-\infty}\frac{(x-\sqrt{x^2+7x})...
- 4,358
1
vote
0
answers
46
views
Mathematica returns zero for small rational number to 1/133 power but not zero [closed]
This small number raised to the 1/133 root is not zero but Mathematica is underflowing with the computation. I assume Mathematica is first computing the quotient numerically, then taking the root:
<...
- 1,169
0
votes
1
answer
65
views
Minimizing a quadratic form: Failed to converge to the requested accuracy or precision within 100 \ iterations
I'm trying to minimize this type of quadratic form:
...
1
vote
0
answers
91
views
How to calculate precise higher derivatives of ParametricNDSolve solution
Higher Derivatives of NDSolve don't match the results from DSolve solution, can I somehow increase the accuracy of numerical method to match arbitrarily high derivatives?
Equation
I am using ...
- 11
0
votes
1
answer
59
views
Issues with Nintegrate - different methods yielding different values (both giving warnings)
I am integrating the following function
\begin{equation}
\frac{1}{2d^{2}}\times\frac{\sqrt{\omega_{c}\left|t_1-t_2\right|}-\sqrt{\pi}e^{\frac{1}{\omega_{c}\left|t_1-t_2\right|}}\text{erfc}\left(\frac{...
- 499
0
votes
2
answers
73
views
Same integral yielding to different results
I am currently working with the following integrals
\begin{equation}
\int_{0}^{\infty} dk\thinspace \frac{k^{3}e^{-2kd}}{\omega^{2}+k^{4}} = \frac{1}{\omega^{2}d^{4}}\int_{0}^{\infty}d\epsilon\...
- 499
1
vote
0
answers
47
views
plot and limit are not in agreement [closed]
I am plotting the following function $\frac{\sqrt{t \text{$\omega_c $}}-\sqrt{\pi } e^{\frac{1}{t \text{$\omega_c $}}} \text{erfc}\left(\frac{1}{\sqrt{t \text{$\omega_c$}}}\right)}{(t \text{$\omega_c$}...
- 499