我剛學C++(第一天在看它,因爲我1周的夏令營年前開始)「富」不是在這個範圍內C++
我轉換程序我正在申報在Java中C++:
#ifndef ADD_H
#define ADD_H
#define _USE_MATH_DEFINES
#include <iostream>
#include <math.h>
using namespace std;
class Evaluatable {
public:
virtual double evaluate(double x);
};
class SkewNormalEvalutatable : Evaluatable{
public:
SkewNormalEvalutatable();
double evaluate(double x){
return 1/sqrt(2 * M_PI) * pow(2.71828182845904523536, -x * x/2);
}
};
SkewNormalEvalutatable::SkewNormalEvalutatable()
{
}
double getSkewNormal(double skewValue, double x)
{
SkewNormalEvalutatable e();
return 2/sqrt(2 * M_PI) * pow(2.71828182845904523536, -x * x/2) * integrate(-1000, skewValue * x, 10000, e);
}
// double normalDist(double x){
// return 1/Math.sqrt(2 * Math.PI) * Math.pow(Math.E, -x * x/2);
// }
double integrate (double start, double stop,
int numSteps,
Evaluatable evalObj)
{
double stepSize = (stop - start)/(double)numSteps;
start = start + stepSize/2.0;
return (stepSize * sum(start, stop, stepSize, evalObj));
}
double sum (double start, double stop,
double stepSize,
Evaluatable evalObj)
{
double sum = 0.0, current = start;
while (current <= stop) {
sum += evalObj.evaluate(current);
current += stepSize;
}
return(sum);
}
// int main()
// {
// cout << getSkewNormal(10.0, 0) << endl;
// return 0;
// }
#endif
的誤差分別爲:
SkewNormal.h: In function 'double getSkewNormal(double, double)' :
SkewNormal.h: 29: error: 'integrate' was not declared in this scope
SkewNormal.h: In function 'double integrate(double, double, int, Evaluatable)':
SkewNormal.h:41: error: 'sum' was not declared in this scope
集成和總和都應該是功能
這裏是Java代碼,或多或少是一樣的:
public static double negativelySkewed(double skew, int min, int max){
return randomSkew(skew) * (max - min) + min;
}
public static double randomSkew(final double skew){
final double xVal = Math.random();
return 2 * normalDist(xVal) * Integral.integrate(-500, skew * xVal, 100000, new Evaluatable() {
@Override
public double evaluate(double value) {
return normalDist(value);
}
});
}
public static double normalDist(double x){
return 1/Math.sqrt(2 * Math.PI) * Math.pow(Math.E, -x * x/2);
}
/** A class to calculate summations and numeric integrals. The
* integral is calculated according to the midpoint rule.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* http://www.corewebprogramming.com/.
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public static class Integral {
/** Returns the sum of f(x) from x=start to x=stop, where the
* function f is defined by the evaluate method of the
* Evaluatable object.
*/
public static double sum(double start, double stop,
double stepSize,
Evaluatable evalObj) {
double sum = 0.0, current = start;
while (current <= stop) {
sum += evalObj.evaluate(current);
current += stepSize;
}
return(sum);
}
/** Returns an approximation of the integral of f(x) from
* start to stop, using the midpoint rule. The function f is
* defined by the evaluate method of the Evaluatable object.
*/
public static double integrate(double start, double stop,
int numSteps,
Evaluatable evalObj) {
double stepSize = (stop - start)/(double)numSteps;
start = start + stepSize/2.0;
return(stepSize * sum(start, stop, stepSize, evalObj));
}
}
/** An interface for evaluating functions y = f(x) at a specific
* value. Both x and y are double-precision floating-point
* numbers.
*
* Taken from Core Web Programming from
* Prentice Hall and Sun Microsystems Press,
* http://www.corewebprogramming.com/.
* © 2001 Marty Hall and Larry Brown;
* may be freely used or adapted.
*/
public static interface Evaluatable {
public double evaluate(double value);
}
我敢肯定這件事情很簡單
而且,我怎麼叫
getSkewNormal(double skewValue, double x)
從SkewNormal之外的文件。H?
您需要聲明一個函數,然後才能用C++調用它。另外,更喜歡'M_E'到'2.71828 ...' – Nemo 2011-06-08 18:04:01