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foucault |
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//--------------------------------------------------------------------------- |
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#pragma hdrstop |
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#include "ot_statistique.h" |
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//--------------------------------------------------------------------------- |
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#pragma package(smart_init) |
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double OT_STATISTIQUE::moyenne (double * x, int n) |
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{ |
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int i; |
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double moyenne_x = 0; |
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for (i=0;i<n;i++) |
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moyenne_x += x[i]; |
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moyenne_x /= n; |
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return moyenne_x; |
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} |
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/// ecart type dans le cas d'une serie discrete |
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/// racine carree de la moyenne de carrés moins le carré de la moyenne |
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double OT_STATISTIQUE::ecart_type (double * x, int n) |
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{ |
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int i; |
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double moyenne_x = moyenne(x,n); |
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double moyenne_x2 = 0; |
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for (i=0;i<n;i++) |
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moyenne_x2 += x[i]*x[i]; |
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moyenne_x2 /= n; |
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return sqrt(moyenne_x2-moyenne_x*moyenne_x); |
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} |
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/// la moyenne des produits moins le produit des moyennes |
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double OT_STATISTIQUE::covariance (double * x, double * y, int n) |
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{ |
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int i; |
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double moyenne_xy = 0; |
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for (i=0;i<n;i++) |
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moyenne_xy += x[i]*y[i]; |
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moyenne_xy /= n; |
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double moyenne_x = 0; |
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for (i=0;i<n;i++) |
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moyenne_x += x[i]; |
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moyenne_x /= n; |
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double moyenne_y = 0; |
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for (i=0;i<n;i++) |
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moyenne_y += y[i]; |
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moyenne_y /= n; |
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return moyenne_xy - moyenne_x * moyenne_y; |
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} |
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/// la moyenne des carrés moins le carré de la moyenne |
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double OT_STATISTIQUE::variance (double * x, int n) |
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{ |
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int i; |
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double moyenne_carres = 0; |
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for (i=0;i<n;i++) |
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moyenne_carres += x[i]*x[i]; |
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moyenne_carres /= n; |
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double moyenne = 0; |
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for (i=0;i<n;i++) |
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moyenne += x[i]; |
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moyenne /= n; |
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return moyenne_carres - moyenne*moyenne; |
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} |
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/// |
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void OT_STATISTIQUE::regression_lineaire(double *x, double *y, int n, double *pente, double *valY0) |
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{ |
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int i; |
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// coef directeur de la droite |
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double a = variance(y,n) / covariance(x,y,n); |
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// b = valeur de y (0) par moindre carrés |
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double b = 0; |
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for (i=0; i<n; i++) |
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b += y[i] - a*x[i]; |
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b /= n; |
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*pente = a; |
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*valY0 = b; |
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} |
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double OT_STATISTIQUE::max(double *x, int n) |
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{ |
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if (n==0) |
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return 0; |
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double max_x = x[0]; |
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for (int i=0;i<n;i++) |
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if (x[i] > max_x) |
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max_x = x[i]; |
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return max_x; |
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} |
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double OT_STATISTIQUE::min(double *x, int n) |
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{ |
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if (n==0) |
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return 0; |
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double min_x = x[0]; |
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for (int i=0;i<n;i++) |
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if (x[i] < min_x) |
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min_x = x[i]; |
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return min_x; |
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} |
