120 lines
3.9 KiB
C
120 lines
3.9 KiB
C
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/*
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* Copyright (C) 2023 Texas Instruments Incorporated - http://www.ti.com/
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*
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* * Neither the name of Texas Instruments Incorporated nor the names of
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* its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _DCL_STABILITY_H_
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#define _DCL_STABILITY_H_
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* \addtogroup DCL_API_MODULE APIs for Digital Control Library
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* @{
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*
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* \file dcl_stability.h
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* \brief Defines polynomial stability functions
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*/
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//--- Polynomial stability functions -----------------------------------------
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//! \brief Determines stability of a first order real polynomial
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//! P(z) = z + a1
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//!
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//! \param[in] a1 Coefficient a1
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//! \return 'true' if the root has magnitude less than 1, 'false' otherwise
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//!
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_DCL_CODE_ACCESS
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bool DCL_isStablePn1(float32_t a1)
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{
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return ((a1 * a1) < 1.0f);
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}
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//! \brief Determines stability of a second order polynomial with real coefficients
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//! P(z) = a0 z^2 + a1 z + a2
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//!
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//! \param[in] a0 Second order coefficient a1
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//! \param[in] a1 First order coefficient a1
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//! \param[in] a2 Coefficient a2
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//! \return 'true' if both roots have magnitude less than 1, 'false' otherwise
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//!
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_DCL_CODE_ACCESS
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bool DCL_isStablePn2(float32_t a0, float32_t a1, float32_t a2)
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{
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float32_t b0, b1, c0;
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b0 = a0 - a2 * a2 / a0;
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b1 = a1 - a1 * a2 / a0;
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c0 = b0 - b1 * b1 / b0;
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return ((a0 > 0.0f) && (b0 > 0.0f) && (c0 > 0.0f));
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}
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//! \brief Determines stability of a third order polynomial with real coefficients
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//! P(z) = a0 z^3 + a1 z^2 + a2 z + a3
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//!
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//! \param[in] a0 Third order coefficient a1
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//! \param[in] a1 Second order coefficient a1
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//! \param[in] a2 First order coefficient a2
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//! \param[in] a3 Coefficient a3
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//! \return 'true' if all roots have magnitude less than 1, 'false' otherwise
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//!
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_DCL_CODE_ACCESS
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bool DCL_isStablePn3(float32_t a0, float32_t a1, float32_t a2, float32_t a3)
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{
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float32_t b0, b1, b2, c0, c1, d0;
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b0 = a0 - a3 * a3 / a0;
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b1 = a1 - a2 * a3 / a0;
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b2 = a2 - a1 * a3 / a0;
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c0 = b0 - b2 * b2 / b0;
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c1 = b1 - b1 * b2 / b0;
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d0 = c0 - c1 * c1 / c0;
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return ((a0 > 0.0f) && (b0 > 0.0f) && (c0 > 0.0f) && (d0 > 0.0f));
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}
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/*
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//! \brief Determines stability of a ZPK3 representation by checking pole magnitude
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//! Located in common/dcl_zpk3.h
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extern bool DCL_isStableZpk3(DCL_ZPK3 *q);
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*/
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/** @} */
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#ifdef __cplusplus
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}
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#endif // extern "C"
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#endif // _DCL_STABILITY_H_
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