信息論與編碼課程設(shè)計-展示頁
2025-08-02 07:20本頁面
【正文】 碼符號次擴展信源無失真編碼器凡是能載荷一定的信息量，且碼字的平均長度最短，可分離的變長碼的碼字集合都可以稱為最佳碼。能獲得最佳碼的編碼方法主要有：香農(nóng)（Shannon）、費諾（Fano）、哈夫曼（Huffman）編碼等。先對信源進(jìn)行編碼，總可以找到一種編碼方法，構(gòu)成唯一可譯碼，使中每個信源符號所需的平均碼長滿足且當(dāng)時有 ，是平均碼長，是對應(yīng)的碼字長度。 （5）取二進(jìn)制數(shù)小數(shù)點后位即為該消息符號的二進(jìn)制碼字。（1）將信源消息符號按其出現(xiàn)的概率大小依次排列：（2）將依次排列的信源符號按概率值分為兩大組，使兩個組的概率之和近似相同，并對各組賦予一個二進(jìn)制碼元“0”和“1”。三、 設(shè)計流程圖 統(tǒng)計信源熵用Matlab讀入一段英文 計算這段文字的字符總數(shù)unm ① ② 統(tǒng)計每種字符的個數(shù)n(i) 算出每種字符的概率p(i) ③ ④ 由信源熵計算公式計算出信源熵 ⑤ 香農(nóng)編碼開始輸入概率矩陣將概率由大到小排列計算累加概率和概率的個數(shù)根據(jù)公式調(diào)用函數(shù)計算碼長用循環(huán)程序編碼并調(diào)整輸出格式 計算信源熵和編碼效率輸出信源熵、編碼效率和碼字結(jié)束 費諾編碼開始輸入概率矩陣將概率由大到小排列計算累加概率和概率的個數(shù)在兩組概率之和近似相等的條件下將概率分為兩組，各賦予0，1兩個碼元將每一大組的的概率重復(fù)上一步操作，直到每組只剩一個概率 用循環(huán)程序編碼并調(diào)整輸出格式計算信源熵和編碼效率輸出信源熵、編碼效率和碼字結(jié)束四、 程序及結(jié)果 統(tǒng)計信源熵的Matlab程序function h=entropy(p)clcfid=fopen(39。,39。)。%c39。%按照字符的ASCII值對字符串排序j=1。 str2(j)=sort_str1(i)。endfor i = 1:length(str2)%length函數(shù)獲取字符串長度 str_num =strfind(sort_str1,str2(i))。endstr2count=count1(3:end)p=count./sum(count)sum(p.*log2(p))%計算信源熵待讀取的英文：The Pressure of Graduate StudentsNow I am a post graduate student, I will graduate next year, so I start to find jobs recently, I feel so much pressure, though I have good education, I still get rejection from the panies. The pressure of graduate students are so heavy, the petition is so fierce that many students can’t get the ideal jobs. They should adjust their strategies.The pressure of graduate students is so heavy. On the one hand, they don’t have experience, so they don’t know how to get the job interview and miss many chances. On the other hand, there are more and more students have high education, some have received higher education, some have
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