Namespaces
Variants
Views
Actions

std::erf

From cppreference.com
< cpp‎ | numeric‎ | math
Revision as of 23:12, 2 November 2012 by P12bot (Talk | contribs)

 
 
 
Common mathematical functions
Functions
Basic operations
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)(C++11)(C++11)
Exponential functions
(C++11)
(C++11)
(C++11)
(C++11)
Power functions
(C++11)
(C++11)
Trigonometric and hyperbolic functions
(C++11)
(C++11)
(C++11)
Error and gamma functions
erf
(C++11)
(C++11)
(C++11)
(C++11)
Nearest integer floating point operations
(C++11)(C++11)(C++11)
(C++11)
(C++11)
(C++11)(C++11)(C++11)
Floating point manipulation functions
(C++11)(C++11)
(C++11)
(C++11)
(C++11)(C++11)
(C++11)
Classification/Comparison
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Macro constants
(C++11)(C++11)(C++11)(C++11)(C++11)
 

Template:ddcl list begin <tr class="t-dsc-header">

<td>
Defined in header <cmath>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td >
float       erf( float arg );
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
double      erf( double arg );
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
long double erf( long double arg );
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
double      erf( Integral arg );
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> Template:ddcl list end

Computes the error function of arg.

Contents

Parameters

arg - floating point value

Return value

The value of the error function of arg, that is
2
π
arg
0
e-t2
dt
.

Example

The following example calculates the probability that a normal variate is on the interval (x1, x2)

#include <iostream>
#include <cmath>
#include <iomanip>
double phi(double x1, double x2)
{
    return (std::erf(x2/std::sqrt(2)) - std::erf(x1/std::sqrt(2)))/2;
}
int main()
{
    std::cout << "normal variate probabilities:\n";
    for(int n=-4; n<4; ++n)
        std::cout << "[" << std::setw(2) << n << ":" << std::setw(2) << n+1 << "]: "
                  << std::setw(5) << std::fixed << std::setprecision(2)
                  << 100*phi(n, n+1) << "%\n";
}

Output:

normal variate probabilities:
[-4:-3]:  0.13%
[-3:-2]:  2.14%
[-2:-1]: 13.59%
[-1: 0]: 34.13%
[ 0: 1]: 34.13%
[ 1: 2]: 13.59%
[ 2: 3]:  2.14%
[ 3: 4]:  0.13%


See also

Template:cpp/numeric/math/dcl list erfc

External links

Weisstein, Eric W. "Erf." From MathWorld--A Wolfram Web Resource.