Transcendental function evaluation

Abstract

The present invention discloses a transcendental function evaluation. In described examples, an apparatus 500 is arranged to generate a linear term, a quadratic term, and a constant term of a transcendental function with, respectively, a first circuit 530, a second circuit 550, and a third circuit 580 in response to least significant bits of an input operand 510 and in response to, respectively, afirst, a second, and a third table value 520 that is retrieved in response to, respectively, a first, a second, and a third index generated in response to most significant bits of the input operand.The third circuit 580 is further arranged to generate a mantissa of an output operand in response to a sum of the linear term, the quadratic term, and the constant term.

Description

technical field Background technique

[0001] A process for performing nonlinear control at a high performance level may evaluate a transcendental function to generate a corrected error signal in a feedback control loop. A corrected error signal is generated in response to a control loop error. function |x| α is a transcendental function that typically uses substantially large numbers of calculations for its computation / evaluation. In digital systems, such transcendental functions can be evaluated by determining a Taylor series expansion, which consumes a high level of computing power and a large number of clock cycles for its execution. Hardware implementations have been proposed for evaluating transcendental functions, such as by using a CORDIC (Coordinate Rotation Digital Computer), which is an iterative process that converges to precision during successive steps. Correspondingly, in the control loop for such as |x| α The evaluation of the transcendental functions of ca...

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