dcl_stability.h

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#ifndef _DCL_STABILITY_H_
#define _DCL_STABILITY_H_
 
#ifdef __cplusplus
extern "C" {
#endif
 
//--- Polynomial stability functions -----------------------------------------
 
_DCL_CODE_ACCESS
bool DCL_isStablePn1(float32_t a1)
{
    return ((a1 * a1) < 1.0f);
}
 
_DCL_CODE_ACCESS
bool DCL_isStablePn2(float32_t a0, float32_t a1, float32_t a2)
{
    float32_t b0, b1, c0;
 
    b0 = a0 - a2 * a2 / a0;
    b1 = a1 - a1 * a2 / a0;
    c0 = b0 - b1 * b1 / b0;
 
    return ((a0 > 0.0f) && (b0 > 0.0f) && (c0 > 0.0f));
}
 
_DCL_CODE_ACCESS
bool DCL_isStablePn3(float32_t a0, float32_t a1, float32_t a2, float32_t a3)
{
    float32_t b0, b1, b2, c0, c1, d0;
 
    b0 = a0 - a3 * a3 / a0;
    b1 = a1 - a2 * a3 / a0;
    b2 = a2 - a1 * a3 / a0;
    c0 = b0 - b2 * b2 / b0;
    c1 = b1 - b1 * b2 / b0;
    d0 = c0 - c1 * c1 / c0;
 
    return ((a0 > 0.0f) && (b0 > 0.0f) && (c0 > 0.0f) && (d0 > 0.0f));
}
 
/*
extern bool DCL_isStableZpk3(DCL_ZPK3 *q);
*/
 
#ifdef __cplusplus
}
#endif // extern "C"
 
#endif // _DCL_STABILITY_H_