．各維的元素數為dici+則a[iii]的地址為
．主對角線上元素的坐標是i=j副對角線上元素的坐標i和j有i+j=n+的關系
（）i=j或i=n+j （≤ij≤n）
（）非零元素分布在兩條主副對角線上除對角線相交處一個元素（下稱中心元素）外其余每行都有兩個元素主對角線上的元素在向量B中存儲的下標是k=i(i=j ≤ij≤n<=k<=n)
副對角線上的元素在中心元素前在向量B中存儲的下標是k=i(i<>j ≤ij≤n/)在中心元素後其下標是k=(i)(i<>jn/+≤ij≤n <=k<=n)
（）aij在B中的位置
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From:http://tw.wingwit.com/Article/program/sjjg/201311/23058.html
