浮点数的详解（国外英文资料）.docVIP

浮点数的详解（国外英文资料） The details of floating-point Numbers are 2007-12-21 22:35 1.what is a floating point In the development of computer system, there have been several methods for expressing real Numbers. Typically, a Fixed Point Number, for example, is relative to a floating Point Number. In this expression, the decimal is fixed to a certain position in the middle of the real number. Currency expression can be used this way, such as 99.00 or 00.99 can be used to express has four Precision (Precision), and after the decimal point two monetary value. Since the decimal point is fixed, the numerical value can be expressed directly with four numerical values. The NUMBER data type in SQL is defined using fixed-point Numbers. There is also a proposed way of expressing the real Numbers using the ratio of two integers. Fixed-point number expression shortcoming lies in its form is too rigid, fixed decimal point position determines the fixed digits of the integer part and decimal part, is not conducive to also express particularly large number or a very small number. In the end, most modern computer systems adopted so-called floating-point expressions. This way to express the real use of scientific notation, which USES a Mantissa (Mantissa), a Base (Base), an index (Exponent) and a said the positive and negative symbols to express the real number. 123.45, for example, can be expressed in decimal science notation 1.2345 by 102, of which 1.2345 is the tail number, 10 is the base, and the 2 is the exponent. Floating point Numbers are used to achieve the effect of floating decimal points, allowing for a flexible representation of a larger set of real Numbers. Tip: the tail is sometimes referred to as the effective number. The number of tails is actually an informal term for effective Numbers. The same numerical value can have a variety of floating-point expression, such as in the example above 123.45 can be expressed as 12.345 x 101,0.12345 x 103 or 1.2345 x 102. Because of this dive