typedef struct {	int ncof,ioff,joff;	float *cc,*cr;} wavefilt;wavefilt wfilt;void pwtset(int n){	void nrerror(char error_text[]);	int k;	float sig = -1.0;	static float c4[5]={0.0,0.4829629131445341,0.8365163037378079,			0.2241438680420134,-0.1294095225512604};	static float c12[13]={0.0,0.111540743350, 0.494623890398, 0.751133908021,		0.315250351709,-0.226264693965,-0.129766867567,		0.097501605587, 0.027522865530,-0.031582039318,		0.000553842201, 0.004777257511,-0.001077301085};	static float c20[21]={0.0,0.026670057901, 0.188176800078, 0.527201188932,		0.688459039454, 0.281172343661,-0.249846424327,		-0.195946274377, 0.127369340336, 0.093057364604,		-0.071394147166,-0.029457536822, 0.033212674059,		0.003606553567,-0.010733175483, 0.001395351747,		0.001992405295,-0.000685856695,-0.000116466855,		0.000093588670,-0.000013264203};	static float c4r[5],c12r[13],c20r[21];	wfilt.ncof=n;	if (n == 4) {		wfilt.cc=c4;		wfilt.cr=c4r;	}	else if (n == 12) {		wfilt.cc=c12;		wfilt.cr=c12r;	}	else if (n == 20) {		wfilt.cc=c20;		wfilt.cr=c20r;	}	else nrerror("unimplemented value n in pwtset");	for (k=1;k<=n;k++) {		wfilt.cr[wfilt.ncof+1-k]=sig*wfilt.cc[k];		sig = -sig;	}	wfilt.ioff = wfilt.joff = -(n >> 1);}