信道容量实验报告.doc

湖南大学大学信息科学与工程学院实验报告第9页 共9页湖 南 大 学信息科学与工程学院实 验 报 告实验名称信道容量的迭代算法课程名称信息论与编码1.实验目的（1）进一步熟悉信道容量的迭代算法；（2）学习如何将复杂的公式转化为程序；（3）掌握C语言数值计算程序的设计和调试技术。2、实验方法硬件：pc机开发平台：visual c+软件编程语言：c语言3、实验要求（1）已知：信源符号个数r、信宿符号个数s、信道转移概率矩阵P。（2）输入：任意的一个信道转移概率矩阵。信源符号个数、信宿符号个数和每个具体的转移概率在运行时从键盘输入。（3）输出：最佳信源分布P*，信道容量C。4. 算法分析1：procedure CHANNEL CAPACITY(r,s,()2：initialize:信源分布=1/r，相对误差门限，C=3：repeat4：5：6：C 7：until 8：output P*= ,C9：end procedure 5. 程序调试1、头文件引入出错f:visualc+channelcpp1.cpp(4) : fatal error C1083: Cannot open include file: unistd.h: No such file or directory#include纠错：/#includef:visualc+channelcpp1.cpp(5) : fatal error C1083: Cannot open include file: values.h: No such file or directory#include纠错：/#include2、变量赋值错误f:visualc+channelcpp1.cpp(17) : error C2065: ij : undeclared identifierf:visualc+channelcpp1.cpp(17) : error C2440: initializing : cannot convert from int to float * Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style castfloat *phi_ij=ij=NULL;纠错：float *phi_ij=NULL;3、常量定义错误f:visualc+channelcpp1.cpp(40) : error C2143: syntax error : missing ; before forfor(i=0;iDELTA)f:visualc+channelCpp1.cpp(84) : error C2021: expected exponent value, not if(fabs(p_j)=DELTA)f:visualc+channelCpp1.cpp(100) : error C2021: expected exponent value, not if(fabs(phi_ijij)=DELTA)f:visualc+channelCpp1.cpp(116) : error C2021: expected exponent value, not while(fabs(C-C_pre)/CDELTA);纠错：#define DELTA 0.000001;F:visualc+channelCpp1.cpp(68) : error C2065: MAXFLOAT : undeclared identifierF:visualc+channelCpp1.cpp(68) : warning C4244: = : conversion from int to float, possible loss of dataC=-MAXFLOAT;纠错：#define MAXFLOAT 1000000;3、引用中文逗号f:visualc+channelcpp1.cpp(60) : error C2018: unknown character 0xa1f:visualc+channelcpp1.cpp(60) : error C2018: unknown character 0xb1f:visualc+channelcpp1.cpp(60) : error C2065: Starting : undeclared identifierf:visualc+channelcpp1.cpp(60) : error C2059: syntax error : .f:visualc+channelcpp1.cpp(60) : error C2017: illegal escape sequencef:visualc+channelcpp1.cpp(60) : error C2018: unknown character 0xa1f:visualc+channelcpp1.cpp(60) : error C2018: unknown character 0xb1 fprintf(stdout,”Starting.n”);纠错：fprintf(stdout,Starting.n);4、没有进行强制转换F:visualc+channelCpp1.cpp(65) : warning C4244: = : conversion from double to float, possible loss of datap_ii=1.0/(float)r;纠错：p_ii=(float)(1.0/(float)r);F:visualc+channelCpp1.cpp(101) : warning C4244: += : conversion from double to float, possible loss of data sumi+=p_jiij*log( phi_ijij)/ log(2.0);纠错：sumi+=(float)(p_jiij*log( phi_ijij)/ log(2.0);F:visualc+channelCpp1.cpp(103) : warning C4244: = : conversion from double to float, possible loss of datasumi=pow(2.0,sumi);纠错:sumi=(float)(pow(2.0,sumi);F:visualc+channelCpp1.cpp(114) : warning C4244: = : conversion from double to float, possible loss of dataC= log(p_j)/ log(2.0);纠错：C= (float)(log(p_j)/ log(2.0);4、表达式错误F:visualc+channelCpp1.cpp(86) : error C2065: phi_ji : undeclared identifierF:visualc+channelCpp1.cpp(86) : error C2109: subscript requires array or pointer typeF:visualc+channelCpp1.cpp(86) : error C2109: subscript requires array or pointer typephi_ijij=p_ii* phi_jiij/p_j;纠错：phi_ijij=p_ii* p_jiij/p_j;F:visualc+channelCpp1.cpp(122) : error C2065: fprint : undeclared identifierF:visualc+channelCpp1.cpp(122) : error C2018: unknown character 0xa1F:visualc+channelCpp1.cpp(122) : error C2018: unknown character 0xb1F:visualc+channelCpp1.cpp(122) : error C2065: The : undeclared identifierF:visualc+channelCpp1.cpp(122) : error C2146: syntax error : missing ) before identifier iterationF:visualc+channelCpp1.cpp(122) : error C2017: illegal escape sequenceF:visualc+channelCpp1.cpp(122) : error C2017: illegal escape sequenceF:visualc+channelCpp1.cpp(122) : error C2018: unknown character 0xa1F:visualc+channelCpp1.cpp(122) : error C2018: unknown character 0xb1fprint(stdout,”The iteration number is %d.nn”,k);纠错：fprintf(stdout,The iteration number is %d.nn,k);F:visualc+channelCpp1.cpp(145) : error C2143: syntax error : missing ) before ; free(p_i);纠错：free(p_i);5、没有返回值F:visualc+channelCpp1.cpp(149) : warning C4508: main : function should return a value; void return type assumed、纠错：return 0;6. 改进程序/*引入头文件*/#include#include#include/*定义常量*/#define DELTA 0.0000001/DELTA为相对误差门限#define MAXFLOAT 1000000;/MAXFLOAT为初始化信道容量值int main( void)/*定义全局变量*/*register允许直接从寄存器中读取变量，提高速率*/register int i,j;/i、j为整型变量register int k;/信道容量迭代计算次数int r,s;/r为信源符号个数，s为新宿符号个数float *p_i=NULL;/r个信源符号发生的概率float *p_ji=NULL;/信源到新宿的信道转移概率矩阵Pfloat *phi_ij=NULL;float C,C_pre,validate;/C为信道容量，C_pre为信道最大容量，validate为判定输入转移概率矩阵是否合法float * sum=NULL;/信源符号所带的全部信息量float p_j;/条件概率/*输入信源符号和新宿符号个数*/printf(请输入信源符号个数r、信宿符号个数s.n);printf(+注意！r必须大于等于s！+n);fscanf(stdin,%d,&r);fscanf(stdin,%d,&s);/*为 p_i,p_ji 和 phi_ij 分配内存空间*/p_i=(float *)calloc(r,sizeof(float);p_ji=(float *)calloc(r,sizeof(float);/*为每个p_ji分配大小为s的内存空间*/for(i=0;ir;i+) p_jii=(float *)calloc(s,sizeof(float);phi_ij=(float *)calloc(r,sizeof(float*);/*输入转移概率矩阵*/for(i=0;ir;i+)/*为每个phi_ij分配大小为s的内存空间*/ phi_iji=(float *)calloc(s,sizeof(float); printf(信道转移概率矩阵P.n); for(i=0;ir;i+) for(j=0;js;j+) fscanf(stdin,%f,&p_jiij); /*判定输入的转移概率矩阵是否正确*/ for(i=0;ir;i+) validate=0.0; for(j=0;j=0)/如果转移概率矩阵的概率和大于1，输入数据不合法 fprintf(stdout,invalid input data.n); exit(-1); /*显示开始计算.*/ fprintf(stdout,Starting.n); /*初始化 p_i 和 phi_ij*/ for(i=0;ir;i+) /* p_i为等概率，即概率为1/r*/ p_ii=(float)(1.0/(float)r); /*初始化信道容量c，迭代次数k和临时变量variable*/ C=-MAXFLOAT; k=0; /* 为sum分配大小为r的内存空间*/ sum=(float *)calloc(r,sizeof(float); /*开始迭代计算*/ do k+;/每进行一次迭代，迭代次数k加1 /* 计算phi_ij(k)*/ for(j=0;js;j+) p_j=0.0; for(i=0;i=DELTA) for(i=0;ir;i+) phi_ijij=p_ii* p_jiij/p_j; else for(i=0;ir;i+) phi_ijij=0.0; /*计算p_i(k+1)*/ p_j=0.0; for(i=0;ir;i+) sumi=0.0; for(j=0;j=DELTA) sumi+=(float)(p_jiij*log( phi_ijij)/ log(2.0); sumi=(float)(pow(2.0,sumi); p_j+=sumi; for(i=0;iDELTA);free(sum); sum=NULL; /*显示结果*/ fprintf(stdout,The iteration number is %d.nn,k);/迭代次数 fprintf(stdout,The capacity of the channel is %.6f bit/symbol:nn,C);/信道容量 fprintf(stdout,The best input probability distribution is :n);/最佳信源分布 for(i=0;i=0;i-) free(phi_iji); phi_iji=NULL; free(phi_ij); phi_ij=NULL; for(i=r-1;i=0;i-) free(p_jii); p_jii=NULL; free(p_ji); p_ji=NULL; free(p_i); p_i=NULL; exit(0); return 0; 7. 实验结果8、 实验结论 信道容量是指信道能无错误传送的最大信息率。对