Questions tagged [floating-point]

Approximate representation of numbers as a fixed number of digits multiplied by a logarithmic scale.

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Numerical Accuracy & Sorting Algorithms?

Sedgewick and Wayne talk about how sorting algorithms and, specifically, priority queues are used in devising ways to improve accuracy in floating-point calculations: https://algs4.cs.princeton.edu/...
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Write the smallest positive number that can be represented by the floating point system

Using a normalised floating point representation box with an 8-bit mantissa and a 4-bit exponent, both stored using two’s complement. (a) Write the smallest positive number that can be represented by ...
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Is the exponent bias $2^{n-1}-1$ or $2^{n-1}$

I'm a bit confused with the exponent bias. The sources I found online claim that it is either $2^{n-1}-1$ or $2^{n-1}$, $n$ is the number of bits used for the exponent. In my book when given examples ...
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Understanding How Double Precision Numbers are Stored in a Computer

I am reading Numerical Analysis by Walter Gautschi. I am somewhat confused by the following quote from page $5$: To increase the precision, one can use two machine registers to represent a machine ...
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1answer
29 views

Question About Floating Point System

I have begun reading Numerical Analysis by Walter Gautschi. On page $3$, the author introduces the floating point number system as follows: a floating point number is a number representible as $$ \...
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Why is there a precision loss for floating-point numbers?

It could be a silly question, yet I'm not able to understand. In modern day, computers, we have integers with million digits length. Even in my ordinary 2GB laptop, I can calculate values of numbers ...
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1answer
38 views

Max flow algorithm for floating-point weights and E~=10*V

Could you, please, suggest a maximum flow algorithm for a graph with floating-point weights and the number of edges approximately equal to the number of vertices? I.e. ...
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1answer
37 views

Normalization in IBM hexadecimal floating point

According to the Wikipedia link of IBM hexadecimal floating point: Consider encoding the value −118.625 as an IBM single-precision floating-point value. The value is negative, so the sign ...
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1answer
30 views

Convert scientific notation decimal number to binary

I'm given the number: $$8.881784197001252 \cdot 10^{-16}$$ I know it is $2^{-50}$ but suppose I didn't know. I need to convert it to binary. One way is to apply the school taught algorithm on the ...
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1answer
42 views

Do all programming languages adhere to the IEEE 754-2008 standard?

I am well aware that the float data type's maximum value is approximately 1.8E308, which means that across the various ...
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0answers
57 views

What are the smallest and biggest negative floating point numbers in IEEE 754 32 bit?

I am stuck with a question that asks for smallest and biggest negative floating point numbers in IEEE 754 32-bit (their representation and decimal numerical value from which one can approximate the ...
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28 views

How can I calculate the exponential integral?

(I'm not sure this is the right forum.) I'm writing a program that uses the prime-counting function. Right now, I'm using x/log(x), but I want to switch to ...
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1answer
22 views

What's the least signifcant bit of a mantissa system?

If Mantissa is a 1-dot-M fixed-point number whose most significant bit is always 1 then, how is the least significant bit calculated? I know the least and most significant bit of the mantissa ...
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Question about machine epsilon

I am studying over my notes, and there is something I don't understand about $e_m$. We represent the floating point numbers as $1.d_1d_2...d_t \times \beta^e$. Now, my professor defines $\epsilon_m$ ...
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1answer
35 views

Floating point arithmetic on division

I am trying to figure out how $(x/y)$ in floating point arithmetic $fl(fl(x) / fl(y))$ where $fl(x) = x(1-\delta_1)$, $fl(y) = y(1-\delta_2)$, $fl = (1-\delta_3)$ I have: $= x/y \cdot ((1-\delta_1)/...
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Is Decimal (correctly-rounded arbitrary precision decimal floating point arithmetic) fixed-point, floating-point or something else?

The Decimal data type I am referring to is GNU MPFR(https://en.wikipedia.org/wiki/GNU_MPFR), or libmpdec (http://www.bytereef.org/mpdecimal/doc/libmpdec/index.html). I have been searching for ...
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1answer
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Smallest integer i stored as a float such that i+1=i

So I had an assignment which asked me to find the smallest integer $i$ which when represented as a float is such that $i+1=i$ My approach- By making a simple C++ program , we get $i=16777216$ or $i=2^...
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2answers
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Why multiplying float number by multiple of 10 seems to preserve better precision?

It is famous that for float numbers: .1 + .2 != .3 but 1+2=3 It seems that multiplying floats by 10 allows you to preserve ...
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4answers
70 views

How does a computer compute negative(-) and positive(+) Infinity?

If we divide (1.0/0.0) we will get +Infinity and if we divide (-1.0/0.0) we will get -Infinity. How does a computer calculate this value internally?
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Can we represent $\sqrt{2}$ exactly even with infinite bits in mantissa [closed]

Can we represent $\sqrt{2}$ exactly even with infinite bits in mantissa in floating point notation or otherwise. We actually have to prove this is not possible. But why can't we if we have infinite ...
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27 views

Floating point substraction

if $x=1.0e38=1.0 * 10^{38}$ and $y=3.0$ i want to find $ (x-x)+y $ and $(x+y)-x$ i think the value of (x-x)+y will be just substract $x-x=0 + y=3.0 = 3.0$ but how can i perfom addition of different ...
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1answer
70 views

Polynomials - using Newton's method, or not?

I have to find a root of polynomial of degree $n\ge2$. I need to write code to calculate the root for different values of $n$. Only 1 real positive solution is needed. I can use general Newton's ...
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How many floating point ops were performed worldwide over a time interval [closed]

I am looking for information regarding the evolution of computing capability. Specifically I would like to know how many floating point operations were performed worldwide from, say, the deployment of ...
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1answer
61 views

Computing an Expression

I am writing code to evaluate the following expression: $$ \frac{(a+b+c)!}{a! b! c!} $$ where $a$, $b$ and $c$ are on the range of $10$ to $500$. The result is going to be a floating point number. ...
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How much can we trust mathematical software when working with large numbers, and how much memory it needs to work with these numbers?

For example, I want to evaluate the expression: $3^{3^{{3}^{3}}}$ so I used wolframalpha.com (it's free, and I don't own any software), which returned the scientific notation of the number above, ...
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numerically stable log1pexp calculation

What are good approximations for computing log1pexp for single precision and double precision floating point numbers? Note: ...
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1answer
87 views

Floating point arithmetic

I need to change x1 = 0.3 and x2 = -0.29 to a FP(floating point) number with one sign bit, a 4 bit mantissa, a 3 bit exponent. The results I got are: x1: 0 001 0011 x2: 1 001 0010 I am also trying ...
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Convert $1.75\times10^{15}$ to IEEE-32 format?

$1.75\times10^{15}$ I know how to convert decimal to binary $(1.75)_{10}$ is equal to $(1.11)_2$ But to represent $10^{15}$ is the main problem for me. I can solve the question but this is the ...
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Guarantees on computing $a+x(b-a)$ in floating point

I want to implement the function $f(x,a,b) = a + x(b-a)$ where all the inputs are floating point (doubles, say), such that (a) $f(0,a,b)=a$ exactly; (b) $f(1,a,b)=b$ exactly; (c) $f(x,a,b) \le f(y,a,b)...
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How does normalised floating point binary work with two's complement?

I'm doing AQA a-level computer science, and the specification for which states that: Exam questions on floating point numbers will use a format in which both the normalised mantissa and exponent are ...
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Where can I find some free benchmarks to evaluate a MCU? [closed]

At present, I'm designing a soft processor with single-precision floating point unit (FPU). I am going to put my soft core into an FPGA and do some performance evaluation. The benchmarks are supposed ...
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119 views

Float number to binary

I would like to convert 0,347 and 0,9828 to binary, how can I do that? I know that sucessive multiplication by 2 can do this, but this method seems very painful and even ineffective since the size of ...
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Stable and fast computation of the squared euclidean distance matrix

Let's say I want to compute the matrix $M$ of the squared euclidean distances between each pair of vectors $(x, y)$ belonging to two sets $X$ and $Y$ respectively. The sets of vectors $X$ and $Y$ have ...
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2answers
361 views

Proof that (x-y)(x+y) is more accurate than x²-y²

I was carrying on my reading of What Every Computer Scientist Should Know About Floating-Point Arithmetic but got stuck on the proof of Theorem 2 (page 34). At some point it says: \begin{align} (x \...
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1answer
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Proof that a guard digit bound the error of subtraction

I was reading What Every Computer Scientist Should Know About Floating-Point Arithmetic, which is extremely interesting. But I have some troubles understanding the proof of Theorem 9 (page 33). First ...
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1answer
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Why isn't it necessary to store an integer part of significant in IEEE754 floating point notation?

We see that there is a sign, exponent, and mantissa part for the notation. But, there is no location for the significant bit. Why isn't it necessary to store an integer part of significant in IEEE754 ...
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Doubt in definition of Float

Can anyone tell the meaning of the bold portion? Float: It is used to store decimal numbers (numbers with floating point value) with single precision.
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Number of FLOPs (floating point operations) for exponentiation

What is the number of floating point operations needed to perform exponentiation (power of)? Assuming multiplication of two floats use one FLOP, the number of operations for $x^n$ will be $n-1$. ...
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2answers
254 views

How to test for overflow when multiplying floats

I am trying to implement a 3-term recurrence relation: $$ p_{n+1} = ap_n + bp_{n-1} $$ This can be implemented as ...
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1answer
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How does IEEE 754 decimal encoding work? [closed]

This may be a silly question, but if a computer works in binary how can you encript numbers using decimal?
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What is the state of the algorithmic art for floating point arithmetic on complex numbers?

Most modern compilers and processors implement the IEEE 754 binary formats for floating point numbers. IEEE 754 guarantees that the addition, subtraction, multiplication, division, and square root ...
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1answer
272 views

Binary Floating Point Range/Precision for 4-bit Mantissa and 4-bit Exponent

I'm trying to understand binary floating point and using just a 4-bit mantissa and a 4-bit exponent (both 2s compliment) to keep things simple. As far as I can tell, the largest denary number I can ...
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2answers
49 views

Floating point precision from rearranging equation

When I run $x^2 - y^2$ with x=8.8888888888 and y=9.9999999999 in python, I get the following result: ...
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1answer
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Why do I get different results from two calculation methods?

I am wondering what the reason for the following is We know that , exponential has a taylor representation : $$exp(x)=1+x+\frac{x^{2}}{2!}+\frac{x^{3}}{3!}+...$$ Using the first n terms , in R , ...
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2answers
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Increased rounding relative error when subtracting

I'm reading the book "Lessons in Scientific Computing" by Schoerghofer and it says: If x and y are real numbers of the same sign, their sum x + y has an absolute error that adds the two ...
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3answers
242 views

IEEE754 representation in hexadecimal?

In class, I've heard hexadecimal representation for IEEE754 mentioned and described in 32bit length as a format that consists of one bit for sign, normalized 6-digit fraction (with an implied leading ...
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1answer
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Addition errors in IEEE754 floating point representation

So in class, we were talking about the idea of floating point precision in IEEE754 format, and how, when some numbers are added, precision is lost. My professor then gave the following example of a ...
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1answer
3k views

Understanding denormalized numbers in floating point representation

I am confused about how denormalized numbers work in floating point representation. I was referring to Stallings book and this article. The book initially explains floating point number format in ...
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Accuracy and performance between a division and subtraction for a ratio in decibels

For comparing two images, one can use the Peak Signal-to-Noise Ratio (PSNR) metric, defined as follows: $\mathrm{PSNR} = 10 \cdot \log_{10}\left(\frac{\mathrm{MAX}^2}{\mathrm{MSE}}\right) = 20 \cdot \...
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2answers
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Algorithm challenge: build a pile of 'n' cubes whose total volume adds up to 'm'

I'm working on solving an algorithm problem defined as follows (important parts in bold): Your task is to construct a building which will be a pile of n cubes. The cube at the bottom will have a ...