Patent ID: 6983298
Filing Date: 2006-01-03
Classification: G06F

Abstract:
1. A method of forming an interpolation value of a function for input values between argument values for which the function value is known, comprising the steps of: storing in a memory function values corresponding to discrete values of an argument of the function for which the function value is known; receiving an input value; determining a first argument value for which the function value is known immediately less than the input value; forming a least significant bit difference between the input value and the first argument value having a predetermined number of less significant bits, each such bit less significant than a least significant bit of the first argument value; determining a second argument value for which the function value is known immediately greater than the input value; recalling from the memory a first function value for the first argument value; recalling from the memory a second function value for the second argument value; forming an absolute value of a difference between the second function value minus the first function value; determining a sign of the difference between the second function value minus the first function value; storing in a memory a set of gradient values for each bit of the absolute value of the difference and each of the predetermined number of less significant bits; recalling from the memory gradient values for the least significant bit difference corresponding to bits where the absolute value of the difference is 1; summing the recalled gradient values; if the sign of the difference is 1, adding the sum of the recalled gradient values to the first function value; and if the sign of the difference is 0, subtracting the sum of the recalled gradient values from the first function value.