Logarithm/inverse-logarithm converter utilizing second-order term and method of using same
First Claim
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1. A logarithm converter, which comprises:
- a memory for storing a plurality of parameters and a plurality of second-order terms, wherein the parameters are calculated using a least squares method to estimate a logarithmic function over a domain of input values, the memory providing as output ones of the parameters and a second-order term which correspond to an input value; and
arithmetic means, operatively coupled to the memory, for generating a log value by performing arithmetic operations on the input value, the ones of the parameters, and the second-order term.
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Abstract
A converter which may be used for implementing either logarithmic or inverse-logarithmic functions is disclosed. The converter includes a memory, a multiplier, and two adders. The memory stores a plurality of parameters and second-order terms which are derived using a least squares method to estimate a logarithmic or inverse-logarithmic function over a domain of input values. A method of computing the parameters and second-order terms is also disclosed.
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Citations
30 Claims
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1. A logarithm converter, which comprises:
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a memory for storing a plurality of parameters and a plurality of second-order terms, wherein the parameters are calculated using a least squares method to estimate a logarithmic function over a domain of input values, the memory providing as output ones of the parameters and a second-order term which correspond to an input value; and arithmetic means, operatively coupled to the memory, for generating a log value by performing arithmetic operations on the input value, the ones of the parameters, and the second-order term. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A logarithm converter for generating a log value corresponding to an input value, the logarithm converter comprising:
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a memory for storing a plurality of second-order terms and a plurality of parameter pairs, wherein each of the parameter pairs is calculated using a least squares method to estimate a logarithmic function over an interval of input values, the memory providing as output a parameter pair and a second-order term which correspond to the input value, wherein the parameter pair has a zero-order parameter and a first-order parameter; a multiplier for multiplying the first-order parameter by a bit slice of the input value to produce a proportional term; a first adder for summing the proportional term and the second-order term to produce a first sum; and a second adder for summing the first sum and the zero-order parameter to produce the log value. - View Dependent Claims (8, 9, 10)
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11. A computing device, which comprises:
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a processing unit for executing a computer operation which utilizes a log value; a computer memory for storing a computer program which includes the computer operation; a bus for connecting the processing unit and the computer memory; and a logarithm converter which receives an input value and includes; a memory for storing a plurality of parameters and a plurality of second-order terms, wherein the parameters are calculated using a least squares method to estimate a logarithmic function over a domain of input values, the memory providing as output ones of the parameters and a second-order term which correspond to the input value; and arithmetic means, operatively coupled to the memory, for generating the log value by performing arithmetic operations on the input value, the ones of the parameters, and the second-order term. - View Dependent Claims (12, 13, 14, 15)
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16. An inverse-logarithm converter, which comprises:
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a memory for storing a plurality of parameters and a plurality of second-order terms, wherein the parameters are calculated using a least squares method to estimate an inverse-logarithmic function over a domain of input values, the memory providing as output ones of the parameters and a second-order term which correspond to an input value; and arithmetic means, operatively coupled to the memory, for generating an inverse-log value by performing arithmetic operations on the input value, the ones of the parameters, and the second-order term. - View Dependent Claims (17, 18, 19, 20, 21, 27, 28)
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22. An inverse-logarithm converter for generating an inverse-log value corresponding to an input value, the inverse-logarithm converter comprising:
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a memory for storing a plurality of second-order terms and a plurality of parameter pairs, wherein each of the parameter pairs is calculated using a least squares method to estimate an inverse-logarithmic function over an interval of input values, the memory providing as output a parameter pair and a second-order term which correspond to the input value, wherein the parameter pair has a zero-order parameter and a first-order parameter; a multiplier for multiplying the first-order parameter by a bit slice of the input value to produce a proportional term; a first adder for summing the proportional term and the second-order term to produce a first sum; and a second adder for summing the first sum and the zero-order parameter to produce the inverse-log value. - View Dependent Claims (23, 24, 25)
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26. A computing device, which comprises:
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a processing unit for executing a computer operation which utilizes an inverse-log value; a computer memory for storing a computer program which includes the computer operation; a bus for connecting the processing unit and the computer memory; and an inverse-logarithm converter which receives an input value and includes; a memory for storing a plurality of parameters and a plurality of second-order terms, wherein the parameters are calculated using a least squares method to estimate an inverse-logarithmic function over a domain of input values, the memory providing as output ones of the parameters and a second-order term which correspond to the input value; and arithmetic means, operatively coupled to the memory, for generating the inverse-log value by performing arithmetic operations on the input value, the ones of the parameters, and the second-order term. - View Dependent Claims (29, 30)
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Specification