C语言求信息熵,条件熵,联合熵.doc

#includestdio.h#includemath.h#define u 20int i,j,n,m;float H_X,H_Y,H_XY,H_XpY,Pypxuu,Pxu,H_YpX,Pyu,Pxpyuu,Pxyuu;/*H_X=H(X)平均自信息；H_XY=H(XY)联合熵;H_XpY=H(X|Y)、H_YpX=H(Y|X)条件熵;Pypxij=P(yj|xi)条件概率;Pxi=P(xi)发xi的概率；H_XpY=H(Y/X)条件熵;Pyj=P(yj)收到yj的概率；Pxpyij=P(xi/yj)条件概率；Pxyij=P(xiyj)联合概率*/*定义以2为底的对数函数*/ float log2(float x) float z; z=(float)(log(x)/log(2); return z;/*求信源熵函数*/float entropy(float *x,int n) float z=0; for(i=1;i=n;i+) z+=(*(x+i)*log2(1/(*(x+i); return z;/*求联合熵的函数*/float joint_entropy(float (*p)u) float z=0; for(i=1;i=n;i+) for(j=1;j=m;j+) z+=*(pi+j)*log2(1/(*(pi+j); return z; main() float s=0; printf(nplease in put the dimension of X and Yn); scanf(%d %d,n,m); printf(nThe dimension of X is n=%dnThe dimension of Y is m=%dnPlease input the condition probability:P(yj/xi),n,m); printf(after you input one number please click the enter)n);/*条件概率P(yj/xi)赋值*/ for(i=1;i=n;i+) for(j=1;j=m;j+) printf(P(y%d/x%d)=,j,i); scanf(%f,Pypxij); printf(please input P(xi):(after you input one number please click the enter)n); for(i=1;i=n;i+) printf(P(x%d)=,i); scanf(%f,Pxi); /*判断输入X的概率是否正确，不正确则退出程序*/ for(i=1;i=n;i+) if(Pxi0)|(Pxi1) printf(Please input right value of probabilityn); goto End_exe; s+=Pxi; if(s-1)*(s-1)0.001) printf(Please input the right value of probabilityn); goto End_exe; for(i=1;i=n;i+) s=0; for(j=1;j=m;j+) s+=Pypxij; if(s-1)*(s-1)0.001) printf(Please input the right value of probabilityn); goto End_exe; /*计算Pyj=P(yj)收到yj的概率；Pxpyij=P(xi/yj)条件概率；Pxyij=P(xiyj)联合概率*/ for(i=1;i=n;i+) for(j=1;j=m;j+) Pxyij=Pypxij*Pxi; printf(Px%dy%d=%fn,i,j,Pxyij); for(j=1;j=m;j+) s=0; for(i=1;i=n;i+) s+=Pxyij; Pyj=s; printf(P(y%d)=%fn,j,Pyj); for(i=1;i=n;i+) for(j=1;j=m;j+) Pxpyij=Pxyij/Pyj; printf(P(x%d/y%d)=%fn,i,j,Pxpyij); /*结束 计算Pyj=P(yj)收到yj的概率； Pxpyij=P(xi/yj)条件概率； Pxyij=P(xiyj)联合概率*/*输出信源熵*/ H_X=entropy(Px,n); printf(nThe entropy of X :H(X)=%fn,H_X); H_Y=entropy(Py,m); printf(nThe entropy of Y :H(Y)=%fn,H_Y);/*输出联合熵*/ H_XY=joint_entropy(Pxy); printf(nThe joint entropy of X and Y :H(XY)=%fn,H_XY);/*输出条件熵*/ H_X