Difference between revisions of "cpp/numeric/math/erf"
From cppreference.com
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===Parameters=== | ===Parameters=== | ||
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| − | {{par | arg | floating point | + | {{par | arg | value of a floating-point or [[cpp/types/is_integral|Integral type]]}} |
{{par end}} | {{par end}} | ||
Revision as of 08:41, 23 January 2014
| Defined in header <cmath>
|
||
| float erf( float arg ); |
(since C++11) | |
| double erf( double arg ); |
(since C++11) | |
| long double erf( long double arg ); |
(since C++11) | |
| double erf( Integral arg ); |
(since C++11) | |
Computes the error function of arg.
Contents |
Parameters
| arg | - | value of a floating-point or Integral type |
Return value
The value of the error function ofarg, that is | 2 |
| √π |
Example
The following example calculates the probability that a normal variate is on the interval (x1, x2)
Run this code
#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
| (C++11)(C++11)(C++11) |
complementary error function (function) |
External links
Weisstein, Eric W. "Erf." From MathWorld--A Wolfram Web Resource.
