void lsp_to_lpc(float *freq,float *ak,int lpcrdr, char *stack)
void lsp_to_lpc(float *freq,spx_coef_t *ak,int lpcrdr, char *stack)
void lsp_to_lpc(float *freq,float *ak,int lpcrdr, char *stack)/*  float *freq 	array of LSP frequencies in the x domain	*//*  float *ak 		array of LPC coefficients 			*//*  int lpcrdr  	order of LPC coefficients 			*/{    int i,j;    float xout1,xout2,xin1,xin2;    float *Wp;    float *pw,*n1,*n2,*n3,*n4=NULL;    int m = lpcrdr/2;    Wp = PUSH(stack, 4*m+2, float);    pw = Wp;    /* initialise contents of array */    for(i=0;i<=4*m+1;i++){       	/* set contents of buffer to 0 */	*pw++ = 0.0;    }    /* Set pointers up */    pw = Wp;    xin1 = 1.0;    xin2 = 1.0;    /* reconstruct P(z) and Q(z) by  cascading second order      polynomials in form 1 - 2xz(-1) +z(-2), where x is the      LSP coefficient */    for(j=0;j<=lpcrdr;j++){       int i2=0;	for(i=0;i<m;i++,i2+=2){	    n1 = pw+(i*4);	    n2 = n1 + 1;	    n3 = n2 + 1;	    n4 = n3 + 1;	    xout1 = xin1 - 2*(freq[i2]) * *n1 + *n2;	    xout2 = xin2 - 2*(freq[i2+1]) * *n3 + *n4;	    *n2 = *n1;	    *n4 = *n3;	    *n1 = xin1;	    *n3 = xin2;	    xin1 = xout1;	    xin2 = xout2;	}	xout1 = xin1 + *(n4+1);	xout2 = xin2 - *(n4+2);	ak[j] = (xout1 + xout2)*0.5;	*(n4+1) = xin1;	*(n4+2) = xin2;	xin1 = 0.0;	xin2 = 0.0;    }}