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Questions tagged [underflow]

An arithmetic underflow is a condition in a computer program where the result of a calculation is a number of smaller absolute value than the computer can actually represent in memory.

In computing, buffer underrun or buffer underflow is a state occurring when a buffer used to communicate between two devices or processes is fed with data at a lower speed than the data is being read from it. This requires the program or device reading from the buffer to pause its processing while the buffer refills.

From Wikipedia

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Explain Change to GNU C++ filebuf::underflow() interacting with filebuf::seekoff()

My company's products run on a number of qualified Linux hardware/software configurations. Historically, the compiler used has been GNU C++. For purposes of this post, let's consider version 3.2.3 the baseline, as our software 'worked as expected'…
Don Wakefield
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At what point should I worry about underflow in numpy values?

I am doing calculations with Python numpy. Here is a resulting numpy array: [ 5.15054786e-11 5.15251385e-11 5.15262922e-11 ..., 5.21100674e-11 5.21097550e-11 5.21088179e-11] Those are pretty tiny. At what point should I worry about…
ShanZhengYang
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Graceful Underflow

I have been searching about this for so long, but i am not able to understand what this question means. Question: Write a program in any language to determine how your computer handles graceful underflow. I understand that a overflow condition is…
SeasonalShot
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Subtract and detect underflow, most efficient way? (x86/64 with GCC)

I'm using GCC 4.8.1 to compile C code and I need to detect if underflow occurs in a subtraction on x86/64 architecture. Both are UNSIGNED. I know in assembly is very easy, but I'm wondering if I can do it in C code and have GCC optimize it in a way,…
kktsuri
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How to detect floating point underflow in C

I need help and sample code on how to detect floating point underflow in standard way with out using third party libraries and exceptions for both signed and unsigned. I googled and found that various authors are talking about "gradual underflow…
venkysmarty
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Why does the NSDecimalNumber 10^-65 squared result in 10^126 instead of resulting in an Underflow Exception?

So here's the code: NSDecimalNumber *test=[[NSDecimalNumber alloc] initWithInt:65]; number3=[[NSDecimalNumber one] decimalNumberByDividingBy:[[[NSDecimalNumber alloc] initWithInt:10]…
classicalpianoguy
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Handling Underflow with HMM Forward-Algorithm

I'm trying to implement the Forward-Algorithm for a Hidden Markov Model (HMM) and I'm facing the underflow issue when filling the alpha table. I normalized the alpha values using the method described in section 6 here but now the resulting sum of…
Ahmad
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Avoiding underflow for joint probabilities using NumPy

I face a problem of estimating a joint probability for independent variables in a simple setup. Currently I have an array of 100 random variables and I would like to obtain their joint probability without failing into the underflow problem. Any…
JustInTime
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How do I evaluate this equation?

I think its pretty self explanatory from the code. Obviously I'm no evaluating the same thing over and over, its just example numbers to explain my problem. I'm guessing its over/underflow but I don't know how to deal with it. double d = (1 /…
Cheetah
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Overflow/underflow in unsigned numbers

So, if you have a carry out of 1 on addition with unsigned numbers, you have overflowed, and if you have a carry out of 0 with subtraction, you have underflowed. Does this work in every case, though? If you do 5-0: 0101 -0000 = 0101 +(1111 +…
Risshuu
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numbers near underflow limit display as `Inf.e-324` in tibble?

Per the docs, "on a typical R platform the smallest positive double is about 5e-324." Given a double vector with values above, near, and below this limit: library(tibble) small_vec <- c(4e-300, 4e-324, 4e-350) small_df <- data.frame(x =…
zephryl
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c++ inconsistent unsigned to signed subtraction results only fails for one permutation

I realize that there is a rule by which numbers with a width smaller than int can be promoted to a wider type for the addition operation. But I cannot fully explain how only one permutation of the following print_unsafe_minus will fail. How is it…
Patrick Parker
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How to deal with the log of a sum of more than two super small probabilities

For some evil reason I need to calculate the log of the sum of 500 super small probabilities, each term computed by dmvnorm(X[,i], mean=rep(0,3), sigma=diag(3)) Sometimes the codes above return 0 due to underflow, but using logarithms will be…
Paw in Data
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Under flow with floating point arithmetic checking

I'm programming a library with multiple instances of long mathematical formulas that sometimes underflow when using doubles. One example could be: (Exp(-a*a) - Exp(-b*b))*Exp(c)*Exp(d) And a,b,c,d also involve some computation of similar type. I…
Radost
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How can I avoid overflow/underflow when computing the euclidean norm of a vector?

I was trying to use log and then take the exp, but that makes only sense if I deal with products or divisions. One would usually define Euclidean_Norm <- function(x) sqrt(sum(x^2)) But I can't handle overflow/underflow. I was thinking to…
JimmyJim
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