## SPecXpc

#### Routine

void SPecXpc (const float ec[], float pc[], int Np)

#### Purpose

Convert prediction error filter coefficients to predictor coefficients

#### Description

The error filter coefficients are related to the predictor filter coefficients by,

                  ec[0]  = 1 (not used)
         pc[0] = -ec[1]
              ...
      pc[Np-1] = -ec[Np]

Predictor coefficients are usually expressed algebraically as vectors with 1-offset indexing. The correspondence to the 0-offset C-arrays is as follows.

      p(1) <==> pc[0]       predictor coefficient corresponding to lag 1
      p(i) <==> pc[i-1]     1 <= i < Np

#### Parameters

-> const float ec[]
  Prediction error (residual) filter coefficients (Np + 1 values). It is considered an error if ec[0] is not equal to 1.
<- float pc[]
  Vector of predictor coefficients (Np values). These are the coefficients of the predictor filter, with pc[0] being the predictor coefficient corresponding to lag 1, and pc[Np-1] corresponding to lag Np.
-> int Np
  Number of predictor coefficients

#### Author / revision

P. Kabal / Revision 1.9 2003/05/09

#### See Also

SPcepXpc, SPcorXpc, SPlsfXpc, SPrcXpc

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