epsilon


Value for epsilon in Python

送分小仙女□ 提交于 2019-12-28 11:48:14
问题 Is there a standard value for (or method for obtaining) epsilon in Python? I need to compare floating point values and want to compare against the smallest possible difference. In C++ there's a function provided numeric_limits::epsilon( ) which gives the epsilon value for any given data type. Is there an equivalent in Python? 回答1: The information is available in sys.float_info, which corresponds to float.h in C99. >>> import sys >>> sys.float_info.epsilon 2.220446049250313e-16 回答2: As strcat

precision of comparing double values with EPSILON in C

做~自己de王妃 提交于 2019-12-24 17:18:58
问题 Doing function that takes 2 arrays (column1 and column2) from struct CSV D and plots the graph from it. Idea is to find max, min values of each array, then break range between min−EPSILON and max+EPSILON in to 600 equal regions, where EPSILON = 10^(−6) Problem is that function does not plot the lowest line properly, I think the issue is when comparing the value from array with min-EPSILON , not sure. Please advice. Here's my code. void do_plot(CSV *D, int column1, int column2) { #define Y

precision of comparing double values with EPSILON in C

拟墨画扇 提交于 2019-12-24 17:18:56
问题 Doing function that takes 2 arrays (column1 and column2) from struct CSV D and plots the graph from it. Idea is to find max, min values of each array, then break range between min−EPSILON and max+EPSILON in to 600 equal regions, where EPSILON = 10^(−6) Problem is that function does not plot the lowest line properly, I think the issue is when comparing the value from array with min-EPSILON , not sure. Please advice. Here's my code. void do_plot(CSV *D, int column1, int column2) { #define Y

Choosing an Epsilon Value for Floating Point Comparisons

谁说我不能喝 提交于 2019-12-22 11:05:10
问题 My team is working with financial software that exposes monetary values as C# floating point doubles. Occasionally, we need to compare these values to see if they equal zero, or fall under a particular limit. When I noticed unexpected behavior in this logic, I quickly learned about the rounding errors inherent in floating point doubles (e.g. 1.1 + 2.2 = 3.3000000000000003). Up until this point, I have primarily used C# decimals to represent monetary values. My team decided to resolve this

How does the epsilon hyperparameter affect tf.train.AdamOptimizer?

梦想的初衷 提交于 2019-12-21 22:18:39
问题 When I set epsilon=10e-8 , AdamOptimizer doesn't work. When I set it to 1, it works just fine. 回答1: t <- t + 1 lr_t <- learning_rate * sqrt(1 - beta2^t) / (1 - beta1^t) m_t <- beta1 * m_{t-1} + (1 - beta1) * g v_t <- beta2 * v_{t-1} + (1 - beta2) * g * g where g is gradient variable <- variable - lr_t * m_t / (sqrt(v_t) + epsilon) The epsilon is to avoid divide by zero error in the above equation while updating the variable when the gradient is almost zero. So, ideally epsilon should be a

Floating point less-than-equal comparisons after addition and substraction

℡╲_俬逩灬. 提交于 2019-12-17 10:06:23
问题 Is there a "best practice" for less-than-equal comparisons with floating point number after a series of floating-point arithmetic operations? I have the following example in R (although the question applies to any language using floating-point). I have a double x = 1 on which I apply a series of additions and subtractions. In the end x should be exactly one but is not due to floating-point arithmetic (from what I gather). Here is the example: > stop_times <- seq(0.25, 2, by = .25) > expr <-

Double.Epsilon for equality, greater than, less than, less than or equal to, greater than or equal to

杀马特。学长 韩版系。学妹 提交于 2019-12-17 00:59:12
问题 http://msdn.microsoft.com/en-us/library/system.double.epsilon.aspx If you create a custom algorithm that determines whether two floating-point numbers can be considered equal, you must use a value that is greater than the Epsilon constant to establish the acceptable absolute margin of difference for the two values to be considered equal. (Typically, that margin of difference is many times greater than Epsilon.) So is this not really an epsilon that could be used for comparisons? I don't

Is Math.Abs(x) < double.Epsilon equivalent to Math.Abs(x) == 0d?

蓝咒 提交于 2019-12-11 08:35:12
问题 After a bit of light reading, this article piqued my interest: I'd have thought that yes, the two statements are equivalent, given MSDN's statement: Represents the smallest positive Double value that is greater than zero. This field is constant. Curious to see what people think. EDIT: Found a computer with VS on and ran this Test. Turns out that yes, as expected, they're equivalent. [Test] public void EpsilonTest() { Compare(0d); Compare(double.Epsilon); Compare(double.Epsilon * 0.5); Compare

C++ next float with numeric_limits / epsilon?

落爺英雄遲暮 提交于 2019-12-10 16:59:40
问题 Consider a "normal" real number TREAL x in C++ (not subnormal and not NaN/Infinite) ( TREAL = float , double , long double ) Is the following the good solution to find the previous and next x from a floating-point point of view ? TREAL xprev = (((TREAL)(1.)) - std::numeric_limits<TREAL>::epsilon()) * x; TREAL xnext = (((TREAL)(1.)) + std::numeric_limits<TREAL>::epsilon()) * x; Thank you very much. 回答1: C99 and C++11 have nextafter, nextafterl and nextafterf functions in <math.h> and <cmath> .

Python epsilon is not the smallest number

陌路散爱 提交于 2019-12-09 16:26:30
问题 What does sys.float_info.epsilon return? On my system I get: >>> sys.float_info.epsilon 2.220446049250313e-16 >>> sys.float_info.epsilon / 2 1.1102230246251565e-16 >>> 0 < sys.float_info.epsilon / 2 < sys.float_info.epsilon True How is this possible? EDIT: You are all right, I thought epsilon does what min does. So I actually meant sys.float_info.min . EDIT2 Everybody and especially John Kugelman, thanks for your answers! Some playing around I did to clarify things to myself: >>> float.hex

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