03.08.2013 Views

Embedded Software and Motor Control Libraries for PXR40xx

Embedded Software and Motor Control Libraries for PXR40xx

Embedded Software and Motor Control Libraries for PXR40xx

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Function GFLIB_Atan_FLT<br />

In order to increase the accuracy of approximation without the need <strong>for</strong> a higher order<br />

polynomial, the interval [0, ∞) is further divided into two intervals: [0, 1] <strong>and</strong> (1, ∞). For<br />

the first interval [0, 1] the rational polynomial approximation directly uses the input<br />

value, while <strong>for</strong> the second interval (1, ∞) the reciprocal input parameter is used as the<br />

input value <strong>for</strong> rational polynomial approximation, <strong>and</strong> the output value is subtracted<br />

from π/2.<br />

The GFLIB_Atan_FLT function uses the rational polynomial approximation as defined in<br />

the following equation:<br />

Equation GFLIB_Atan_Eq1<br />

The rational polynomial approximation coefficients used <strong>for</strong> GFLIB_Atan_FLT<br />

calculation, are noted in Table 4-43.<br />

Table 4-43. Rational polynomial approximation coefficients<br />

a 1 a 2 a 3 a 4 a 5 a 6<br />

48.70107004 49.53262637 9.40604244 65.76631639 21.58787406 48.70107004<br />

<strong>Embedded</strong> <strong>Software</strong> <strong>and</strong> <strong>Motor</strong> <strong>Control</strong> <strong>Libraries</strong> <strong>for</strong> <strong>PXR40xx</strong>, Rev. 1.0<br />

244 Freescale Semiconductor, Inc.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!