C语言求信息熵,条件熵,联合熵

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#include#include#define u 20int i,j,n,m;float H_X,H_Y,H_XY,H_XpY,Pypx[u][u],Px[u],H_YpX,Py[u],Pxpy[u][u],Pxy[u][u];/*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;Pypx[i][j]=P(y[j]|x[i])条件概率;Px[i]=P(x[i])发x[i]的概率；H_XpY=H(Y/X)条件熵;Py[j]=P(y[j])收到y[j]的概率；Pxpy[i][j]=P(x[i]/y[j])条件概率；Pxy[i][j]=P(x[i]y[j])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+=*(p[i]+j)*log2(1/(*(p[i]+j))); } return z; }main(){ float s=0; printf("\nplease in put the dimension of 'X' and 'Y'\n"); scanf("%d %d",&n,&m); printf("\nThe dimension of X is n=%d\nThe dimension of Y is m=%d\nPlease input the condition probability:P(y[j]/x[i]),",n,m); printf("(after you input one number please click the 'enter')\n");/*条件概率P(y[j]/x[i])赋值*/ for(i=1;i<=n;i++) {for(j=1;j<=m;j++) {printf("P(y[%d]/x[%d])=",j,i); scanf("%f",&Pypx[i][j]); } } printf("please input P(x[i]):(after you input one number please click the 'enter')\n"); for(i=1;i<=n;i++) {printf("P(x[%d])=",i); scanf("%f",&Px[i]); }/*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((Px[i]<0)||(Px[i]>1)) {printf("Please input right value of probability\n"); goto End_exe; } s+=Px[i]; } if((s-1)*(s-1)>0.001) {printf("Please input the right value of probability\n"); goto End_exe; } for(i=1;i<=n;i++) {s=0; for(j=1;j<=m;j++) {s+=Pypx[i][j]; } if((s-1)*(s-1)>0.001) {printf("Please input the right value of probability\n"); goto End_exe; } }/*计算Py[j]=P(y[j])收到y[j]的概率；Pxpy[i][j]=P(x[i]/y[j])条件概率；Pxy[i][j]=P(x[i]y[j])联合概率*/ for(i=1;i<=n;i++) {for(j=1;j<=m;j++) {Pxy[i][j]=Pypx[i][j]*Px[i]; printf("Px[%d]y[%d]=%f\n",i,j,Pxy[i][j]); } } for(j=1;j<=m;j++) { s=0; for(i=1;i<=n;i++) s+=Pxy[i][j]; Py[j]=s; printf("P(y[%d])=%f\n",j,Py[j]); } for(i=1;i<=n;i++) {for(j=1;j<=m;j++) {Pxpy[i][j]=Pxy[i][j]/Py[j]; printf("P(x[%d]/y[%d])=%f\n",i,j,Pxpy[i][j]); } }/*结束 计算Py[j]=P(y[j])收到y[j]的概率； Pxpy[i][j]=P(x[i]/y[j])条件概率； Pxy[i][j]=P(x[i]y[j])联合概率*//*输出信源熵*/ H_X=entropy(Px,n); printf("\nThe entropy of X :H(X)=%f\n",H_X); H_Y=entropy(Py,m); printf("\nThe entropy of Y :H(Y)=%f\n",H_Y);/*输出联合熵*/ H_XY=joint_entropy(Pxy); printf("\nThe joint entropy of X and Y :H(XY)=%f\n",H_XY);/*输出条件熵*/ H_XpY=H_XY-H_Y; H_YpX=H_XY-H_X; printf("\nThe conditional entropy:\nH(X/Y)=%f\t\tH(Y/X)=%f\n",H_XpY,H_YpX);End_exe:;} 关 键 词： C语言求信息熵条件熵联合熵

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