Mathematical questions concerning floating point numbers, a finite approximation of the real numbers used in computing.

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-5
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0answers
29 views

Floating point representations of some numbers [on hold]

What are the representations of the following in floating point representation: $505000$ $-37200000$ $0.000107$ $0.0029$
11
votes
4answers
715 views

why is $2.2250738585072014\text{e}{-308}$ not a number? [on hold]

In programming the min value of a float is: $$2.2250738585072014\text{e}{-308}$$ but when I type this into a calculator, it says Not a Number. what I am wondering ...
2
votes
0answers
28 views

Can trigonometric functions for double precision be implemented in terms of those for single precision?

In some program environments like GLSL there is support for single and double precision numbers for arithmetic and square roots computation, but only single precision trigonometric functions are ...
2
votes
1answer
73 views

Name of function $(1+x)^n-1$

Is there any name for this formula $$(1+x)^n-1$$ When working with floating point numbers this can be calculated with much better precision for very small $|x|<1$ values using Taylor series ...
0
votes
2answers
36 views

Simplifying a decimal number under modular arithmetic – $9.9 \pmod{13}$

Can you please help me simplify the relation $9.9 \pmod{13}$? It may seem like a stupid question (!) but your answers will help me very much. Thank you.
0
votes
1answer
15 views

approximation using floating point arithmetic

Let $x=2.14366$ and $y=2.14363$ and $d=x-y.$ If $d*$ is the value of d computed using $5-$digit decimal floating point arithmetic, find the relative error. For this question I know how to calculate ...
0
votes
1answer
36 views

Floating point number,Mantissa,Exponent

In this computer, numbers are stored in 12-bits. We will also assume that for a floating point (real) number, 6 bits of these bits are reserved for the mantissa (or significand) with 2^(k-1)-1 as the ...
2
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1answer
34 views

Audio frequency increment yielding wrong results

I am writing something in the ChucK programming language, which is designed specifically for audio time functions (in this case, hertz). I'm having a really difficult time with a mathematical ...
2
votes
3answers
58 views

Why do I get a big relative error for my function? (Numerical Analisys - floating point)

When evaluating on the computer the following function: $$f(x)=\frac{x^2}{(\cos(\sin(x)))^2-1}$$ there is a big relative error for values $x\approx0$ (values very close to zero). I used the Taylor ...
-2
votes
2answers
206 views

Convert decimal to Binary Floating Point - 8 Bit [closed]

I am trying to convert +3.5 to binary floating point, but im struggling to find the exponent. (8 Bit) Where 1st bit is the Sign, 3 bits for Exponent and 4 bits for Mantissa. Hope somebody can explain ...
0
votes
1answer
18 views

Precision and Accuracy

How would I go about calculating the precision and accuracy of a given number? For example 0.05 has an accuracy of 2 and a precision of 3. 1 has an accuracy of 0 and a precision of 1. Is ...
1
vote
2answers
59 views

How to calculate the inverse of sum of a Kronecker product and a diagonal matrix

I want to calculate the inverse of a matrix of the form $S = (A\otimes B+C)$, where $A$ and $B$ are symetric and invertible, $C$ is a diagonal matrix with positive elements. Basically if the ...
0
votes
0answers
46 views

Is is possible to define a sign convention for eigenvectors calculated with a small uncertainty?

I'm working with a numerical method that involves the diagonalization of a real, symmetric $n \times n$ matrix $H$. Now obviously the sign of the (normalized) eigenvectors $\phi_i$ is not well ...
0
votes
1answer
17 views

Storing a real matrix - fl notation

I have two matrix $A$ and $B$ and $fl(A), fl(B)$ denote the stored version them, respectively. Let $fl(AB)$ be the stored version of the product of $A$ and $B$. Is it true that $fl(AB) = fl(A) * ...
1
vote
0answers
25 views

What is the short name for a set of all floating-point numbers?

We can name the set of all real numbers $\mathbb{R}$, and the set of all integers $\mathbb{Z}$. Is there a commonly accepted short name for the set of all IEEE 754 floating point numbers? I understand ...
0
votes
1answer
284 views

Convert hexadecimal numbers to floating-point format using single-precision IEEE 754 format

I need help with converting hexadecimal numbers to floating-point format using single-precision IEEE 754 format. Hex numbers such as 312A. how do I go about converting it? I know how to convert from ...
0
votes
1answer
256 views

How to convert from floating point binary to decimal in half precision(16 bits)?

I'm trying to convert a 16 bit precision binary number to decimal format however I am completely failing to do so. The binary I'm trying to convert is $0101011101010000$ My current method is: ...
6
votes
1answer
137 views

Explain why catastrophic cancellation happens

After my own research, the following picture emerges as the most frequently used example of catastrophic cancellation (It is indeed used in my class). Could anyone explain why the plot takes that ...
0
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0answers
34 views

Binary to Decimal Floating Point Number

I seem to be having difficulties trying to figure this out: I have a Binary 0101011101010000 and I'm trying to compute the decimal floating point number, in the IEEE-754 format Can somebody help? ...
0
votes
1answer
42 views

How can I add the following 32-bit IEEE floating-point numbers?

How can I add the following two 32-bit IEEE floating-point numbers in binary? FEDCBA98(base 16) + 89ABCDEF(base 16) = a 33-bit binary number. How can this be possible?
0
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1answer
20 views

How would you convert the following 32-bit IEEE floating-point to decimal form?

I have got -1.101 1100 1011 1010 1001 1000 * 2^(9) How can I convert this to decimal form?
1
vote
1answer
43 views

Gaps between successive floating point numbers

(all numbers discussed are in decimal) lets say we have a floating point data type that is like : m * 10 ^ e ...
0
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2answers
33 views

Floating Point Calculation

Take the polynomial $x^2+(-4*10^3)x+2)$. On the floating point system, b=10, m=4, e=4, if I wanted to find the roots using the quadratic formula what would be the values of the roots? I got 3.999 as ...
0
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1answer
20 views

Selecting denominator for relative error margins

When looking at this page: http://floating-point-gui.de/errors/comparison/ there are values a, and b that are being compared ...
0
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0answers
15 views

Number Systems and Floating Point Arethmetic

I am confused about the term of finite precision number, is that the same with the floating point number? Moreover, I have a number system: ...
1
vote
0answers
24 views

smallest poisitive integer does not belong in floating point system F

A floating-point number system F is a subset of real numbers whose elements have the form: $x=\pm(m/\beta^t)\beta^e$ base (beta), precision (t), and exponent range (emin and emax). The mantissa m ...
0
votes
1answer
75 views

Convergence and limit of Muller sequence

The Muller sequence is given by the recursive definition: $U(n+1)=111-\frac{1130}{U(n)}+\frac{3000}{U(n)U(n-1)}$ with $U(0)=5.5$ and $U(1)=\frac{61}{11}$. This sequence is interesting in ...
1
vote
1answer
46 views

Entropy of floating number array

I am familiar with shanon's definition of entropy. $$ H(P) = - \sum_{i=1}^n p_i \cdot \log_2(\mathcal p_i) $$ I am today in the situation that I'd like to compute an entropy like function but for a ...
2
votes
4answers
93 views

How to extract fraction from a floating point number

I'm making some tests with float type (floating point number) with programming and in some of my tests I need to extract the fraction that originates the float value. Let $ x $ be a floating point ...
0
votes
0answers
75 views

Different SVD results in Matlab

my question relates to calculating SVD in Matlab. I have been reading a lot and somehow I have jumbled up all the facts. It would be great if you experts could get me to the right track. My task is ...
2
votes
2answers
103 views

Floating point arithmetic: $(x-2)^9$

This is taken from Trefethen and Bau, 13.3. Why is there a difference in accuracy between evaluating near 2 the expression $(x-2)^9$ and this expression: $$x^9 - 18x^8 + 144x^7 -672x^6 + 2016x^5 - ...
0
votes
1answer
208 views

Converting double precision IEEE 754 hex to base 10 with repeating decimals

The number is 0x4001 8CCC CCCC CCCC. So far I have the stored exponent as 1000000000 which equals ...
1
vote
0answers
32 views

Machine Floating Point Theorem

Completely stuck on this floating point question. Let $x \in \mathbb{R}$ have the following floating point representation: $$ x = (-1)^s[0.a_1a_2\dots a_ta_{t+1}\dots]\cdot \beta^e $$ [Where $\beta$ ...
0
votes
1answer
29 views

Finite binary representation of float number

How can I prove that float number $x$ has the finite binary representation if and only if it is written like that: $ x = m / 2^n $, where $m, n \in \mathbb N$. Should I consider something like 3 ...
2
votes
3answers
289 views

What is the maximum difference between two successive real numbers in the given floating point representation?

The following is a scheme for floating point number representation using 16 bits. Sign :- Bit 15 Exponent:-Bit 14-9 Mantissa :- Bit 8-0 Let $s, e,$ and $m$ be the numbers represented in binary in ...
6
votes
1answer
188 views

How to calculate floating point numbers?

Here are two locations in small memory: 0110 | 1111 1110 1101 0011 0111 | 0000 0110 1101 1001 Interpret locations 6 and 7 as an IEEE floating point number. ...
1
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5answers
65 views

Not clear on what we mean with numbers with infinite digits

I am confused on a rather simplistic question. 1/3 = 0.333333333333 to infinity. So it has infinite digits. How is it possible to multiply such a number with another one and get a finite number? 6/3 = ...
1
vote
1answer
28 views

How to interpret fractional number of bits of precision

In double-precision floating-point format there're effective $53$ bits of mantissa stored. This lets us estimate maximum number of decimal digits of precision available: ...
2
votes
1answer
102 views

Accurate floating-point linear interpolation

I want to perform a simple linear interpolation between $A$ and $B$ (which are binary floating-point values) using floating-point math with IEEE-754 rounding rules, as accurately as possible. Please ...
1
vote
1answer
62 views

Converting 16bit float to Base10 and vice versa

Hi! I have some difficulties understanding how I'm supposed to calculate this 16bit float to base10. This is something that is coming up on a test so I would be pleased to learn how this is supposed ...
5
votes
1answer
1k views

What is the most significant digit?

What is the most significant digit of $$0.00234$$ I have a problem of figuring out where it is $0$ or $2$.
0
votes
0answers
72 views

Overflow and underflow of a probability value

I am evaluating the probability that the minimum of a process is a above a a barrier $\log(H)$. The probability is given by $$P_i=1-\exp\left(-2\frac{(\log(H)-x)(\log(H)-x_b)}{\tau\sigma^2}\right).$$ ...
2
votes
1answer
123 views

Given the normalised floating point number system, calculate smallest possible value of y - x

First I present the problem and then my workings and thoughts: Given the normalized floating point number system $(\beta, t, L, U) = (10, 7, -6, 4)$ where $\beta$ is the base and $t$ is the ...
0
votes
3answers
98 views

Is this approach for testing orthogonality/parallelity of vectors wrong as I think?

In a math book four methods are written for testing parallelity/orthogonality of two vectors that are(notice $\vec v$ and $\vec w$ are approximations of vectors and we have x,y and z components of ...
0
votes
1answer
64 views

testing parallelity/perpendicularity of two 3D vectors with lengths close to zero using dot product

as u know dot product and vector norm(euclidean) definitions are as following: $ \vec v . \vec w = \left\lVert \vec v \right\rVert \times \left\lVert \vec w \right\rVert \times \cos\theta = (v_x ...
2
votes
1answer
41 views

Question about making a custom 'formula'

I am working on some program for myself, and I am stuck on one thing, which I am not sure how to make exactly, I do know how to calculate it manually on paper, but I don't know any kind of formula or ...
2
votes
1answer
84 views

Checking if the Hessian is the derivative of the gradient

Suppose $f: \Bbb R^n \to \Bbb R$. I have a code that computes the gradient of $f$. I have another code that computes the Hessian of $f$ times a vector. Now I want to check if they are correct. ...
0
votes
2answers
73 views

Find point in 3D plane

I have four points in a 3D space, example: $$(0,0,1),\ (1,0,1),\ (1,0,2)\ \mbox{and}\ (0,0,2).$$ Then I have a 2D position on that square plane: $$x = 0.5,\ y = 0.5.$$ I need to find out the 3D ...
2
votes
2answers
59 views

binary and floating point representation

suppose that we have following binary digits $00011001.110 $,we can do following thing $00011001.110=1\cdot2^4+1\cdot2^3+1\cdot2^0+1\cdot2^{-1}+1\cdot2^{-2}=25.75$ then what does means? We then ...
1
vote
1answer
29 views

Comparison between float point numbers

How can I demostrate that given two numbers A and B, if A <= B, then fl(A) <= fl(B). fl(A) is the float point representation of A. Which is equal to A(1+x), and |x| <= the machine epsilon ...