| 摘要 |
PURPOSE:To perform the square root arithmetic at high speed by obtaining the temporary square root of data from a data table and then obtaining a real square root through the convergent calculation using a recurrence formula. CONSTITUTION:The n-bit data X<2> is supplied and the square root of upper 16 bits of the data X<2> is retrieved out of a data table. Then the lower (n-16)bits of the data X<2> are all set at 0. Thus the square root X1 of the data X<2>1 is obtained. Here the retrieved square root is shifted by (n-16)/2 bits and (n-15)/2 bits when the remaining (n-16) bits are even or odd respectively. Thus a square root X1 is obtained. In the same way, the square root X2 of the data X<2>2 is obtained when lower (n-32) bits of the data (X<2>-X<2>1) are all set at 0. Then the initial value Xe(0) of the repetitive arithmetic is set equal to (X1+X2) with a desired square root set at Xe(n). An equation I is calculated and the convergence of an equation 2 is decided. if the convergence of the equation 2 is confirmed, the Xe(n) of that time point is defined as the square root X of the data X<2>.
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