# Lecture4 - CMPSC/MATH 451 Numerical Computations Lecture 4 Prof Kamesh Madduri REVIEW 2 Floating-point numbers 3 IEEE-754(1985 Representation

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CMPSC/MATH 451 Numerical Computations Lecture 4 Aug 29, 2011 Prof. Kamesh Madduri

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REVIEW 2
Floating-point numbers 3

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IEEE-754(1985) Representation Exponent is stored in “ biased format ”: a bias value is added to the actual exponent. Single-precision : bias is 127 ; the stored exponent in the 8-bit field lies in [0, 255]. Normalized representation: the leading ‘1’ is not stored. Single-precision example (Source: http:// en.wikipedia.org/wiki/IEEE_754-1985) 4
Rounding rules 5

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e to the pi minus pi Source: XKCD, http://www.xkcd.com/217/ 6
Machine precision 7

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Subnormals and Gradual Underflow Normalization causes gap around zero in floating-point system Denormalized numbers: Allow leading digit to be zero when exponent is at its minimum value (E=L) . Gap is then filled in by subnormal/ denormalized floating-point numbers A floating point system with denormalized numbers is said to exhibit gradual underflow 8
Exceptional Values IEEE floating-point standard provides

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## This note was uploaded on 01/19/2012 for the course CMPSC 451 taught by Professor Staff during the Spring '08 term at Pennsylvania State University, University Park.

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Lecture4 - CMPSC/MATH 451 Numerical Computations Lecture 4 Prof Kamesh Madduri REVIEW 2 Floating-point numbers 3 IEEE-754(1985 Representation

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