Questions related to `long double` floating-point data-type (numbers) as commonly found in languages like C and C++. Sometimes referred to as quadruple-precision floating-point data-type (numbers).
Questions tagged [long-double]
162 questions
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votes
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machine epsilon - long double in c++
I wanted to calculate the machine Epsilon, the smallest possible number e that gives 1 + e > 1 using different data types of C++: float, double and long double.
Here's my code:
#include
template
T machineeps() {
T epsilon =…
bambuk
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4 answers
Objective C: Creating Long Double uses Decimal Method
How do I create the following method?
I have tried to use modf(n, 1) or modf(n, 2) but those both return an error of "Passing argument 2 of modf makes pointer from integer without a cast.
Heres the method:
(BOOL) numberHasDecimal: (long double) n…
michaellindahl
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2 answers
C long double in golang
I am porting an algorithm from C to Go. And I got a little bit confused. This is the C function:
void gauss_gen_cdf(uint64_t cdf[], long double sigma, int n)
{
int i;
long double s, d, e;
//Calculations ...
for (i = 1; i < n - 1;…
user5817854
0
votes
2 answers
Appending long double literal suffix to user inputs in c++
I have a class that has a long double vector:
MyClass{
vector myvec;
public:
MyClass(){ //Constructor }
// Some memeber functions that operate on the vector
};
I have overloaded the input operator an I'm taking…
Anjoys
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C - Long double min and max value
Is correct that min and max value of a long double are like double ones? They use 8 byte each other and max arrive at about E308 (10^308). Long double should use 16byte and arrive at >E4000, shouldn't it? Or it depends from the computer? I check…
Gianmi
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2 answers
Output long double to console
I tried to output a long double to the console directly using qDebug() and indirectly via QString::number() but both do not accept long double.
Is it true that there is no easy way of printing a long double floating point number to the console using…
Silicomancer
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If I'm trying to replicate a program in another language. Is it unwise to use more precision?
I'm in the process of converting a program from Scilab code to C++ and it's essential for me to maintain the results produced by Scilab.
I'm aware that Scilab uses IEEE 754 double precision and that C++ doubles (although not required to) are…
Paul Warnick
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1 answer
returns long double instead of double
I am writing a program in c++ where I want to find the epsilon of my pc.
I want the result to be double precision (which is 2.2204460492503131 E-16) but instead the output is 1.0842 E-019 which is the epsilon in long double precision.
My program is…
Jon Snow
- 101
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1 answer
Format specifier %Lf for long double in C is not working as if expected
While studying the C essentials from online video, the author shared the code below to find the difference between float, double and long double.
I ran this program in Eclispse running in 64 bit Windows 10 Laptop.
#include
#include…
prasanth_ntu
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1 answer
Long double reseting to 0 after assignment
I've been tinkering around with some disease models in C/C++ and would like to get more precision out of it. I thought about using long doubles, for the 80-bit precision (I'm using cygwin`s GCC 4.8.3), but after making a calculation with it, I get a…
Pedro
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3 answers
What is wrong with this expression? "if (factorarray[x]%2 == 0 && factorarray[x]%3 ==0..."
Here is the code:
#include
#include
#include
using namespace std;
class Project3
{
public:
void factorcalc()
{
while (i<5000000){
++i;
factor = prime/i;
if (factor…
Bernardo Pliego-Garcia
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0
votes
0 answers
How can I change the displayed value of a double when outputting to the console in Eclipse Kepler, C++, (mac OS X)?
Here is my code:
#include
#include
using namespace std;
class Project3
{
public:
long double divbythree()
{
while (i
Bernardo Pliego-Garcia
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0
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0 answers
print long double on windows
I use Microsoft Visual Studio 2010 and Intel C++ Compiler XE 14.0. Project configuration is ‘x64’. I need to work with the long double data type. I added a compile option /Qlong_double and wrote a test example:
long double ld = 2;
long…
Konstantin Isupov
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3 answers
Using strtol to get long double in c++
I am trying to get the long double out of an array.
long double num;
char * pEnd;
char line[] = {5,0,2,5,2,2,5,4,5,.,5,6,6};
num = strtold(line1, &pEnd);
For some reason the num i am getting is rounded to 502522545.6
I am quite new to C++…
olv1do
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0
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3 answers
how to parse a long double from scientific notation
I have a text file with numbers in scientific notation stored as a string of characters, some of which have up to 20 digits. For example, 2.3456789e-015. I need to convert this into a long double in order to perform some mathematical operations on…
oneb1got
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