1,527 questions
Best practices
3
votes
7
replies
98
views
IEEE754 floating point to struct and vice versa
I have started an own libc for the purpose of education and for further bare-metal projects. Now I want implement the math library (libm). For easier working with IEEE754 depending if the target ...
2
votes
1
answer
176
views
Binary serialization of floating point data containing NaNs - is normalization required?
While looking for information about how to create a NaN value in C++, I discovered three functions defined in the C++ standard library that can be used to create a NaN with a specific "payload&...
- 63
8
votes
1
answer
185
views
Does the MSVC implementation of `signaling_NaN` comply with the the latest IEEE floating-point standard?
As far as I can tell, the MSVC implementation of signaling_NaN does not comply with IEEE 754-2019, the latest version of the IEEE floating-point standard.
Unfortunately, I do not have a copy of the ...
- 2,517
1
vote
2
answers
98
views
How to get consistent scientific notation with limited precision in Bigloo Scheme?
I'm working with floating-point numbers in Bigloo Scheme, and I encountered a precision issue when performing a simple multiplication:
(* 0.005 1e-9)
;; => 5.0000000000000005e-12
I was expecting ...
0
votes
0
answers
48
views
How to make TypeORM auto-fixing all floating-point values according to their db schema type?
Not sure if that is possible at all?...
It is typical problem - when value in db is 4.725 but in UI it shows 4.7250000000000005.
And there are lot of other value examples which generating such kind of ...
- 459
6
votes
1
answer
192
views
Good practices guidelines for `ffast-math`
I am writing C++ header-only library doing some floating-point math. Since the library is header-only I realized that the library user sooner or later will include it into his project where -ffast-...
- 1,052
3
votes
2
answers
133
views
How to trigger exactly only *one* SSE-exception
I've written a little test program that tiggers FPU-exceptions through feraiseexcept():
#include <iostream>
#include <cfenv>
using namespace std;
int main()
{
auto test = []( int exc,...
3
votes
3
answers
156
views
c++ std::stof() throws out_of_range for 5.87747175e-39
Consider the following code
#include <iostream>
int main()
{
const std::string s("5.87747175e-39");
float f = std::stof(s);
std::cout << s << " - " <<...
- 1,542
1
vote
3
answers
221
views
Is Math.sqrt(x) and Math.pow(x, 0.5) equivalent?
In ECMAScript, given a non-negative, finite double x, is the following assertion always true?
Math.sqrt(x) === Math.pow(x, 0.5)
I know that both Math.sqrt() and Math.pow() are implementation-...
- 178
8
votes
1
answer
168
views
If x*y ≠ 2ⁿ, does it follow that x * y = ((x * y) / y) * y under IEEE 754 semantics?
This is a follow-up to my previous question here. Additional restrictions highlighted in bold.
Given two nonzero, finite, double-precision (a.k.a. binary64) floating point numbers x and y, is it ...
- 8,917
7
votes
1
answer
137
views
Is it always true that x * y = ((x * y) / y) * y under IEEE 754 semantics?
Given two nonzero, finite, double-precision floating point numbers x and y, is it always true that the equality
x * y == ((x * y) / y) * y
holds under default IEEE 754 semantics?
I've searched ...
- 8,917
2
votes
1
answer
223
views
Why does Math.pow(10, -4) produce different results in JavaScript and C#?
I noticed that the result of Math.pow(10, -4) differs between JavaScript and C#.
JavaScript Math.pow
C# Math.Pow
In JavaScript, it seems the result is expressed as an approximation, possibly due to ...
- 37
1
vote
2
answers
121
views
Java Double Precision - Rounding - %f specifier
Numbers sometimes cannot be expressed exactly when they are represented in double precision or single precision. Of course working with bigdecimal is a solution, I know that.
Let's come to my question:...
- 105
2
votes
1
answer
113
views
float16_t rounding on ARM NEON
I am implementing emulation of ARM float16_t for X64 using SSE; the idea is to have bit-exact values on both platforms. I mostly finished the implementation, except for one thing, I cannot correctly ...
- 2,718
3
votes
2
answers
122
views
Floating Point: Why does the implicit 1 change the value of the fractional part?
I was reading about the floating point implementation from the comments of a ziglings.org exercise, and I came across this info about it.
// Floating further:
//
// As an example, Zig's f16 is a IEEE ...
- 186