 
/****************************************************************************** 
    params->data.F32[0] = So; 
    params->data.F32[1] = Zo; 
    params->data.F32[2] = Xo; 
    params->data.F32[3] = Yo; 
    params->data.F32[4] = 1 / SigmaX; 
    params->data.F32[5] = 1 / SigmaY; 
    params->data.F32[6] = Sxy; 
    params->data.F32[7] = length; 
    params->data.F32[8] = theta; 
*****************************************************************************/ 
 
# define PM_MODEL_FUNC       	  pmModelFunc_STRAIL
# define PM_MODEL_FLUX       	  pmModelFlux_STRAIL
# define PM_MODEL_GUESS      	  pmModelGuess_STRAIL
# define PM_MODEL_LIMITS     	  pmModelLimits_STRAIL
# define PM_MODEL_RADIUS     	  pmModelRadius_STRAIL
# define PM_MODEL_FROM_PSF   	  pmModelFromPSF_STRAIL
# define PM_MODEL_PARAMS_FROM_PSF pmModelParamsFromPSF_STRAIL
# define PM_MODEL_FIT_STATUS      pmModelFitStatus_STRAIL

psF32 PM_MODEL_FUNC(psVector *deriv, 
			 const psVector *params, 
			 const psVector *x) 
{ 
    psF32 *PAR = params->data.F32; 
 
    psF32 trailLength = PAR[7]; 
    psF32 theta = PAR[8]; 
 
    psF32 x0 = PAR[2];  //streak center 
    psF32 y0 = PAR[3];  //streak center 
 
    //S values (1/sigma for x and y case, sigma for xy case) 
    psF32 sx = PAR[4];   
    psF32 sy = PAR[5];   
    psF32 sxy = PAR[6];  
 
    psF32 sinT=sin(theta); 
    psF32 cosT=cos(theta); 
    psF32 sin2T=sin(2.0*theta); 
    psF32 cos2T=cos(2.0*theta); 
 
    //    printf("Trying object at %4.1f,%4.1f with length %3.1f and angle %1.3f\r", x0, y0, length, theta); 
 
    //current location relative to trail center 
    psF32 X  = x->data.F32[0] - x0; 
    psF32 Y  = x->data.F32[1] - y0; 
 
    //x' and y' location (trail-orienter coords) 
    psF32 xs = X*cosT + Y*sinT; 
    psF32 ys = -1.0*X*sinT + Y*cosT; 
 
    //initialize variables to be changed below 
    psF32 x1 = 0; 
    psF32 y1 = 0; 
    psF32 px = 0; 
    psF32 py = 0; 
    psF32 z  = 0; 
    psF32 zx = 0; 
    psF32 t  = 0; 
    psF32 tx = 0; 
    psF32 r  = 0; 
    psF32 rx = 0; 
    psF32 f  = 0; 
 
    psF32 sxrot = 0; 
    psF32 syrot = 0; 
    psF32 sxyrot = 0; 
    psF32 dsxrot = 0; 
    psF32 dsyrot = 0; 
    psF32 dsxyrot = 0; 
 
    //    psF32 Rx = 0; 
    //    psF32 Ry = 0; 
    //    psF32 Rxy = 0; 
 
 
    //calculate new S values (1/sigma) for rotated frame 
    psF32 sxrotsq = PS_SQR(cosT*sx) + PS_SQR(sinT*sy) + cosT*sinT*sxy; 
    psF32 syrotsq = PS_SQR(cosT*sy) + PS_SQR(sinT*sx) - cosT*sinT*sxy; 
 
    //    psF32 testtwo=10.1; 
    //    psF32 testone=fabsf(testtwo); 
    //    fprintf (stderr, "Test: %f is the absolute value of %f?\n",testone,testtwo); 
    if (sxrotsq<0) { 
      sxrot = sqrt(-(sxrotsq)); 
      syrot = sqrt(syrotsq); 
      fprintf (stderr, "error in sxrotsq: Neg,  sxrotsq=%f sx=%f sy=%f sxy=%f theta=%f\n",sxrotsq,sx,sy,sxy,theta); 
    } else if (syrotsq<0) { 
      sxrot = sqrt(sxrotsq); 
      syrot = sqrt(-(syrotsq)); 
      fprintf (stderr, "error in syrotsq: Neg,  syrotsq=%f sx=%f sy=%f sxy=%f theta=%f\n",syrotsq,sx,sy,sxy,theta); 
    } else if (sxrotsq==0){ 
      sxrot = 0.01; 
      syrot = sqrt(syrotsq); 
      fprintf (stderr, "error in sxrotsq: Zero,  sxrotsq=%f \n",sxrotsq); 
    } else if (syrotsq==0) { 
      syrot = 0.01; 
      sxrot = sqrt(sxrotsq); 
      fprintf (stderr, "error in syrotsq: Zero,  syrotsq=%f \n",syrotsq); 
      //      return(0); 
    }else { 
      sxrot = sqrt(sxrotsq); 
      syrot = sqrt(syrotsq); 
    } 
 
    sxyrot = sxy*cos2T + (PS_SQR(sy) - PS_SQR(sx))*sin2T; 
 
      if (isnan(sxrot)) { 
	fprintf (stderr, "error in sxrot  syrot=%f sx=%f sy=%f sxy=%f cosT=%f sinT=%f\n",syrot,sx,sy,sxy,cosT,sinT); 
      } else if (isnan(syrot)) { 
	fprintf (stderr, "error in syrot  sxrot=%f sx=%f sy=%f sxy=%f cosT=%f sinT=%f\n",sxrot,sx,sy,sxy,cosT,sinT); 
      }  
 
    //calculate length of pipe (not of trail motion) 
    psF32 length = trailLength - 2.0*2.0/sxrot; 
 
 
    if (xs < length/(-2.0)) { 
      x1 = (xs+length/2.0)*cosT - ys*sinT; //Endpoint1 
      y1 = (xs+length/2.0)*sinT + ys*cosT; //Endpoint1 
      //1.6 factor comes from by-eye testing of fits, sqrt from the later squaring of it 
      //1.6 ~= phi (golden mean)...coincidence? 
      px = sxrot*x1/sqrt(1.6); 
      py = syrot*y1; 
 
      //first find out what the falloff in the x direction is... 
      zx  = 0.5*PS_SQR(px); 
      tx = 1 + zx + zx*zx/2.0 + zx*zx*zx/6.0; 
      rx = 1.0 / (tx + zx*zx*zx*zx/24.0); 
 
      //...and now in the y direction 
      z  = 0.5*PS_SQR(py)+sxyrot*x1*y1; 
      t  = 1 + z + z*z/2.0; 
      r  = 1.0 / (t + z*z*z/6.0); /* exp (-Z) */ 
      f  = PAR[1]*rx*r + PAR[0]; 
 
    } else if (xs > length/2.0){ 
      x1 = (xs-length/2.0)*cosT - ys*sinT; //Endpoint2 
      y1 = (xs-length/2.0)*sinT + ys*cosT; //Endpoint2 
      px = sxrot*x1/sqrt(1.6); 
      py = syrot*y1; 
      zx  = 0.5*PS_SQR(px); 
      tx = 1 + zx + zx*zx/2.0 + zx*zx*zx/6.0; 
      rx = 1.0 / (tx + zx*zx*zx*zx/24.0); 
 
      z  = 0.5*PS_SQR(py)+sxyrot*x1*y1; 
      t  = 1 + z + z*z/2.0; 
      r  = 1.0 / (t + z*z*z/6.0); /* exp (-Z) */ 
      f  = PAR[1]*rx*r + PAR[0]; 
 
      if (isnan(r)) { 
	fprintf (stderr, "error in +r  t=%f z=%f\n",t,z); 
      }  
 
    } else { 
      x1 = -ys*sinT; 
      y1 = ys*cosT;  
      px = sx*x1; 
      py = sy*y1; 
      z  = 0.5*PS_SQR(px) + 0.5*PS_SQR(py) + sxy*x1*y1; 
      t  = 1 + z + z*z/2.0; 
      r  = 1.0 / (t + z*z*z/6.0); /* exp (-Z) */ 
      rx = 1.0;  //so that dF/dF0 can be generalized 
      f  = PAR[1]*r + PAR[0]; 
 
      if (isnan(r)) { 
	fprintf (stderr, "error in midr  t=%f z=%f\n",t,z); 
      }  
    } 
 
     
    //ok...so this is df/dPAR[X] 
    if (deriv != NULL) { 
        psF32 q = 1; 
	//stable 
        deriv->data.F32[0] = +1.0; 
        deriv->data.F32[1] = +r * rx; 
 
	  if (isnan(deriv->data.F32[0])) { 
	    fprintf (stderr, "error in deriv0\n"); 
	  } else if (isnan(deriv->data.F32[1])) { 
	    fprintf (stderr, "error in deriv1 r=%f rx=%f\n",r,rx); 
	  }  
 
	dsxrot = 2.0*PS_SQR(sy)*sinT*cosT - 2.0*PS_SQR(sx)*sinT*cosT + sxy*(PS_SQR(cosT)-PS_SQR(sinT)); 
	dsyrot = 2.0*PS_SQR(sx)*sinT*cosT - 2.0*PS_SQR(sy)*sinT*cosT - sxy*(PS_SQR(cosT)-PS_SQR(sinT)); 
	dsxyrot = 2.0*cos2T*(PS_SQR(sy)-PS_SQR(sx)) - 2.0*sxy*sin2T; 
 
	  if (isnan(dsxrot)) { 
	    fprintf (stderr, "error in dsxrot\n"); 
	  } else if (isnan(dsyrot)) { 
	    fprintf (stderr, "error in dsyrot\n"); 
	  } else if (isnan(dsxyrot)) { 
	    fprintf (stderr, "error in dsxyrot\n"); 
	  }  
	 
	//initialize variables definied in the if statements 
	//	psF32 XXX=0; 
	//	psF32 YYY=0; 
 
	   
	// variable over piecewise func 
	// change the endcaps to be 4th order gaussians with sxrot_fit=1.6*sxrot 
	// y' direction can ge adequately modelled by a 3rd order gaussian with syrot 
	if (xs < length/(-2.0)) { 
	   
	  q=PAR[1]*r*rx; 
	  deriv->data.F32[2] = -q*(rx*tx/1.6*x1*PS_SQR(sxrot) + r*t*y1*sxyrot); 
	  deriv->data.F32[3] = -q*r*t*(y1*PS_SQR(syrot) + x1*sxyrot); 
	  deriv->data.F32[4] = -q*(rx*tx*x1*sx*PS_SQR(cosT)/1.6*(x1+2.0*cosT/sxrot) + r*t*y1*sx*sinT*(y1*sinT+2.0*PS_SQR(syrot)*PS_SQR(cosT)/(sxrot*sxrot*sxrot)) + 2.0*r*t*sx*(-1.0*x1*y1*sin2T+y1*sxyrot*(cosT*cosT*cosT)/(sxrot*sxrot*sxrot)+x1*sxyrot*(sinT*cosT*cosT)/(sxrot*sxrot*sxrot))); 
	  deriv->data.F32[5] = -q*(rx*tx*x1*sy*PS_SQR(sinT)/1.6*(x1+2.0*cosT/sxrot) + r*t*y1*sy*(y1*PS_SQR(cosT)+2.0*PS_SQR(syrot)*(sinT*sinT*sinT)/(sxrot*sxrot*sxrot)) + 2.0*r*t*sy*(x1*y1*sin2T+y1*sxyrot*(sinT*sinT*cosT)/(sxrot*sxrot*sxrot)+x1*sxyrot*(sinT*sinT*sinT)/(sxrot*sxrot*sxrot))); 
	  deriv->data.F32[6] = -q*(rx*tx*x1*cosT*sinT/3.2*(x1+2.0*cosT/sxrot) + r*t*y1*cosT*sinT/2.0*(-y1+2.0*PS_SQR(syrot)*sinT/(sxrot*sxrot*sxrot)) + r*t*(x1*y1*cos2T+y1*sxyrot*sinT*cosT*cosT/(sxrot*sxrot*sxrot)+x1*sxyrot*sinT*sinT*cosT/(sxrot*sxrot*sxrot))); 
	  deriv->data.F32[7] = -q*(rx*tx*PS_SQR(sxrot)*x1*cosT/3.2 + r*t*PS_SQR(syrot)*y1*sinT/2.0 + r*t*sxyrot/2.0*(y1*cosT+x1*sinT)); 
	  deriv->data.F32[8] = -q*(rx*tx*x1/3.2*(x1*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))+PS_SQR(sxrot)*(2.0*cosT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot) - sinT*length)) + r*t*y1/2.0*(y1*(2.0*sinT*cosT*(PS_SQR(sx)-PS_SQR(sy))-sxy*(PS_SQR(cosT)-PS_SQR(sinT)))+PS_SQR(syrot)*(2.0*sinT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot)+cosT*length)) + r*t*(2.0*x1*y1*(cos2T*(PS_SQR(sy)-PS_SQR(sx))-sxy*sin2T)+y1*sxyrot/2.0*(2.0*cosT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot)-length*sinT)+x1*sxyrot/2.0*(2.0*sinT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot)+length*cosT))); 
 
	  /*	  if (isnan(deriv->data.F32[2])) { 
	    fprintf (stderr, "error in deriv2\n"); 
	  } else if (isnan(deriv->data.F32[3])) { 
	    fprintf (stderr, "error in deriv3\n"); 
	  } else if (isnan(deriv->data.F32[4])) { 
	    fprintf (stderr, "error in deriv4\n"); 
	  } else if (isnan(deriv->data.F32[5])) { 
	    fprintf (stderr, "error in deriv5\n"); 
	  } else if (isnan(deriv->data.F32[6])) { 
	    fprintf (stderr, "error in deriv6\n"); 
	  } else if (isnan(deriv->data.F32[7])) { 
	    fprintf (stderr, "error in deriv7\n"); 
	  } else if (isnan(deriv->data.F32[8])) { 
	    fprintf (stderr, "error in deriv8\n"); 
	  } 
	  */ 
	     
 
 
	} else if (xs > length/2.0){ 
 
	  q=PAR[1]*r*rx; 
	  deriv->data.F32[2] = -q*(rx*tx/1.6*x1*PS_SQR(sxrot) + r*t*y1*sxyrot); 
	  deriv->data.F32[3] = -q*r*t*(y1*PS_SQR(syrot) + x1*sxyrot); 
	  deriv->data.F32[4] = -q*(rx*tx*x1*sx*PS_SQR(cosT)/1.6*(x1-2.0*cosT/sxrot) + r*t*y1*sx*sinT*(y1*sinT-2.0*PS_SQR(syrot)*PS_SQR(cosT)/(sxrot*sxrot*sxrot)) + 2.0*r*t*sx*(-1.0*x1*y1*sin2T-y1*sxyrot*(cosT*cosT*cosT)/(sxrot*sxrot*sxrot)-x1*sxyrot*(sinT*cosT*cosT)/(sxrot*sxrot*sxrot))); 
	  deriv->data.F32[5] = -q*(rx*tx*x1*sy*PS_SQR(sinT)/1.6*(x1-2.0*cosT/sxrot) + r*t*y1*sy*(y1*PS_SQR(cosT)-2.0*PS_SQR(syrot)*(sinT*sinT*sinT)/(sxrot*sxrot*sxrot)) + 2.0*r*t*sy*(x1*y1*sin2T-y1*sxyrot*(sinT*sinT*cosT)/(sxrot*sxrot*sxrot)-x1*sxyrot*(sinT*sinT*sinT)/(sxrot*sxrot*sxrot))); 
	  deriv->data.F32[6] = -q*(rx*tx*x1*cosT*sinT/3.2*(x1-2.0*cosT/sxrot) + r*t*y1*cosT*sinT/2.0*(-y1-2.0*PS_SQR(syrot)*sinT/(sxrot*sxrot*sxrot)) + r*t*(x1*y1*cos2T-y1*sxyrot*sinT*cosT*cosT/(sxrot*sxrot*sxrot)-x1*sxyrot*sinT*sinT*cosT/(sxrot*sxrot*sxrot))); 
	  deriv->data.F32[7] = q*(rx*tx*PS_SQR(sxrot)*x1*cosT/3.2 + r*t*PS_SQR(syrot)*y1*sinT/2.0 + r*t*sxyrot/2.0*(y1*cosT+x1*sinT)); 
	  deriv->data.F32[8] = -q*(rx*tx*x1/3.2*(x1*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))-PS_SQR(sxrot)*(2.0*cosT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot) - sinT*length)) + r*t*y1/2.0*(y1*(2.0*sinT*cosT*(PS_SQR(sx)-PS_SQR(sy))-sxy*(PS_SQR(cosT)-PS_SQR(sinT)))-PS_SQR(syrot)*(2.0*sinT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot)+cosT*length)) + r*t*(2.0*x1*y1*(cos2T*(PS_SQR(sy)-PS_SQR(sx))-sxy*sin2T)-y1*sxyrot/2.0*(2.0*cosT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot)-length*sinT)-x1*sxyrot/2.0*(2.0*sinT*(2.0*sinT*cosT*(PS_SQR(sy)-PS_SQR(sx))+sxy*(PS_SQR(cosT)-PS_SQR(sinT)))/(sxrot*sxrot*sxrot)+length*cosT))); 
 
 
	  /*	  if (isnan(deriv->data.F32[2])) { 
	    fprintf (stderr, "error in deriv2\n"); 
	  } else if (isnan(deriv->data.F32[3])) { 
	    fprintf (stderr, "error in deriv3\n"); 
	  } else if (isnan(deriv->data.F32[4])) { 
	    fprintf (stderr, "error in deriv4\n"); 
	  } else if (isnan(deriv->data.F32[5])) { 
	    fprintf (stderr, "error in deriv5\n"); 
	  } else if (isnan(deriv->data.F32[6])) { 
	    fprintf (stderr, "error in deriv6\n"); 
	  } else if (isnan(deriv->data.F32[7])) { 
	    fprintf (stderr, "error in deriv7\n"); 
	  } else if (isnan(deriv->data.F32[8])) { 
	    fprintf (stderr, "error in deriv8\n"); 
	  } 
	  */ 
 
	} else { 
	  // this does not change from before, as the y' falloff can be modelled by the standard 3rd order gaussian  
	  // note difference from a pure gaussian: q = PAR[1]*r 
	  q = PAR[1]*r*r*t; 
	  deriv->data.F32[2] = q*(PS_SQR(sx*sinT)*x1 - PS_SQR(sy)*y1*cosT*sinT - sxy*x1*sinT*cosT + sxy*y1*PS_SQR(sinT)); 
	  deriv->data.F32[3] = q*(-1*PS_SQR(sx)*x1*sinT*cosT + PS_SQR(sy*cosT)*y1 + sxy*x1*PS_SQR(cosT) - sxy*y1*sinT*cosT); 
	  deriv->data.F32[4] = -q*sx*PS_SQR(x1); 
	  deriv->data.F32[5] = -q*sy*PS_SQR(y1); 
	  deriv->data.F32[6] = -q*x1*y1; 
	  deriv->data.F32[7] = 0; 
	  deriv->data.F32[8] = -q*( PS_SQR(sx)*x1*(xs*sinT - ys*cosT) + PS_SQR(sy)*y1*(xs*cosT - ys*sinT) + sxy*x1*(xs*cosT - ys*sinT) + sxy*y1*(xs*sinT - ys*cosT) ); 
 
	  if (isnan(deriv->data.F32[2])) { 
	    fprintf (stderr, "error in deriv2\n"); 
	  } else if (isnan(deriv->data.F32[3])) { 
	    fprintf (stderr, "error in deriv3\n"); 
	  } else if (isnan(deriv->data.F32[4])) { 
	    fprintf (stderr, "error in deriv4\n"); 
	  } else if (isnan(deriv->data.F32[5])) { 
	    fprintf (stderr, "error in deriv5\n"); 
	  } else if (isnan(deriv->data.F32[6])) { 
	    fprintf (stderr, "error in deriv6\n"); 
	  } else if (isnan(deriv->data.F32[7])) { 
	    fprintf (stderr, "error in deriv7\n"); 
	  } else if (isnan(deriv->data.F32[8])) { 
	    fprintf (stderr, "error in deriv8\n"); 
	  } 
 
 
	} 
    } 
    return(f); 
} 
 
//fixed  
// XXX this needs to apply the axis ratio limits to prevent avoid solutions
# define AR_MAX 20.0
# define AR_RATIO 0.99
bool PM_MODEL_LIMITS (psMinConstraintMode mode, int nParam, float *params, float *beta) {
 
    float beta_lim = 0;
    float params_min = 0;
    float params_max = 0;
    float f1, f2, q1;
    float q2 = 0;
 
    // we need to calculate the limits for SXY specially
    if (nParam == PM_PAR_SXY) {
	f1 = 1.0 / PS_SQR(params[PM_PAR_SYY]) + 1.0 / PS_SQR(params[PM_PAR_SXX]);
	f2 = 1.0 / PS_SQR(params[PM_PAR_SYY]) - 1.0 / PS_SQR(params[PM_PAR_SXX]);
	q1 = PS_SQR(f1)*AR_RATIO - PS_SQR(f2);
	assert (q1 > 0);
	q2  = 0.5*sqrt (q1);
    }

    switch (mode) {
      case PS_MINIMIZE_BETA_LIMIT:
	switch (nParam) {
	  case PM_PAR_SKY:  beta_lim = 1000;   break;
	  case PM_PAR_I0:   beta_lim = 10000;    break; // too small?
	  case PM_PAR_XPOS: beta_lim = 50;     break;
	  case PM_PAR_YPOS: beta_lim = 50;     break;
	  case PM_PAR_SXX:  beta_lim = 0.5;    break;
	  case PM_PAR_SYY:  beta_lim = 0.5;    break;
	  case PM_PAR_SXY:  beta_lim = 1.0;    break;  // set this to q2?
	  case 7:           beta_lim = 10.0;     break;
	  case 8:           beta_lim = M_PI/6.0; break;

	  default:
	    psAbort("invalid parameter %d for beta test", nParam);
	}
	if (fabs(beta[nParam]) > fabs(beta_lim)) {
	    beta[nParam] = (beta[nParam] > 0) ? fabs(beta_lim) : -fabs(beta_lim);
	    return false;
	}
	return true;
      case PS_MINIMIZE_PARAM_MIN:
	switch (nParam) {
	  case PM_PAR_SKY:  params_min = -1000; break;
	  case PM_PAR_I0:   params_min =     0; break;
	  case PM_PAR_XPOS: params_min =  -100; break;
	  case PM_PAR_YPOS: params_min =  -100; break;
	  case PM_PAR_SXX:  params_min =   0.5; break;
	  case PM_PAR_SYY:  params_min =   0.5; break;
	  case PM_PAR_SXY:  params_min =  -5.0; break; // set this to -q2?
	  case 7:           params_min =     0;  break;
	  case 8:           params_min = -1*M_PI; break;

	  default:
	    psAbort("invalid parameter %d for param min test", nParam);
	}
	if (params[nParam] < params_min) {
	    params[nParam] = params_min;
	    return false;
	}
	return true;
      case PS_MINIMIZE_PARAM_MAX:
	switch (nParam) {
	  case PM_PAR_SKY:  params_max =   1e5; break;
	  case PM_PAR_I0:   params_max =   1e8; break;
	  case PM_PAR_XPOS: params_max =   1e4; break;
	  case PM_PAR_YPOS: params_max =   1e4; break;
	  case PM_PAR_SXX:  params_max =   100; break;
	  case PM_PAR_SYY:  params_max =   100; break;
	  case PM_PAR_SXY:  params_max =   +q2; break;
	  case 7:           params_max =   150; break;
	  case 8:           params_max =  M_PI; break;
	  default:
	    psAbort("invalid parameter %d for param max test", nParam);
	}
	if (params[nParam] > params_max) {
	    params[nParam] = params_max;
	    return false;
	}
	return true;
      default:
	psAbort("invalid choice for limits");
    }
    psAbort("should not reach here");
    return false;
}

//fixed 
psF64 PM_MODEL_FLUX(const psVector *params) 
{ 
    float f, norm, z; 
 
    psF32 *PAR = params->data.F32; 
 
    psF64 A1   = PS_SQR(PAR[4]); 
    psF64 A2   = PS_SQR(PAR[5]); 
    psF64 A3   = PS_SQR(PAR[6]); 
    psF32 Rx=2./PS_SQR(PAR[4]);  
    psF32 Ry=2./PS_SQR(PAR[5]);  
    psF32 Rxy=PAR[6]; 
 
 
    psF32 theta = PAR[8];  
    psF32 sinT=sin(theta); 
    psF32 cosT=cos(theta); 
 
    psF32 Syrot = ( PS_SQR(sinT)/Rx + PS_SQR(cosT)/Ry - Rxy*sinT*cosT );  //rotated sigma y 
 
    psF64 A4   = Syrot*PAR[7]; 
 
    psF64 Area = 2.0 * M_PI / sqrt(A1*A2 - A3) + A4; 
    // Area is equivalent to 2 pi sigma^2 + rectangle 
 
    // the area needs to be multiplied by the integral of f(z) 
    norm = 0.0; 
    for (z = 0.005; z < 50; z += 0.01) { 
	f = 1.0 / (1 + z + z*z/2 + z*z*z/6); 
	norm += f; 
    } 
    norm *= 0.01; 
     
    psF64 Flux = params->data.F32[1] * Area * norm; 
 
    return(Flux); 
} 
 
// define this function so it never returns Inf or NaN 
// also prevent 0 returns, and just send a v small number 
// return the radius which yields the requested flux 
 
//fixed, but need to change how it is called to accomodate 2 radii 
psF64 PM_MODEL_RADIUS  (const psVector *params, psF64 flux) 
{ 
    if (flux <= 0) return (1.0); 
    if (params->data.F32[1] <= 0) return (1.0); 
    if (flux >= params->data.F32[1]) return (1.0); 
 
    psF32 *PAR = params->data.F32; 
    psF32 sigma  = sqrt(2.0) * hypot (1.0 / params->data.F32[4], 1.0 / params->data.F32[5]); 
 
    psF32 theta = PAR[8];  
    psF32 sinT=sin(theta); 
    psF32 cosT=cos(theta); 
    psF32 Rx=2./PS_SQR(PAR[4]); 
    psF32 Ry=2./PS_SQR(PAR[5]); 
    psF32 Rxy=PAR[6]; 
    psF32 length=PAR[7]; 
 
    psF32 Syrot = ( PS_SQR(sinT)/Rx + PS_SQR(cosT)/Ry - Rxy*sinT*cosT );  //rotated sigma y 
 
    psF64 radius = 0; 
    if (flux > 0){ 
      psF64 radius0 = sigma * sqrt (2.0 * log(params->data.F32[1] / flux)); 
      psF64 radius1 = Syrot * sqrt (2.0 * log(params->data.F32[1] / flux)); 
 
      if (radius0 > radius1) { 
	radius=radius0+length/2.0; 
      } else { 
	radius=radius1+length/2.0; 
      }  
    } else { 
      radius = 1000; 
    } 
 
    if (radius < 0.01){ 
      radius = 0.01; 
    } 
 
    if (isnan(radius)) { 
      fprintf (stderr, "error in code\n"); 
    } 
    return (radius); 
} 
 
//fixed I think...no good way of guessing as far as I can tell 
bool PM_MODEL_GUESS (pmModel *model, pmSource *source)
{ 
    pmMoments *Smoments = source->moments; 
    psF32     *params  = model->params->data.F32; 
 
    psEllipseAxes axes; 
    psEllipseShape shape; 
    psEllipseMoments moments; 
 
    moments.x2 = PS_SQR(Smoments->Sx); 
    moments.y2 = PS_SQR(Smoments->Sy); 
    moments.xy = Smoments->Sxy; 
    //sometimes these moment inputs are zero...why? 
 
    // solve the math to go from Moments To Shape 
    // limit the axis ratio to 20 (a guess)
    axes = psEllipseMomentsToAxes(moments, 20.0); 
    shape = psEllipseAxesToShape(axes); 
 
    params[0] = Smoments->Sky; 
    params[1] = Smoments->Peak - Smoments->Sky; 
    params[2] = Smoments->x; 
    params[3] = Smoments->y; 
    params[7] = 2 * axes.major;  
    params[8] = axes.theta; 
 
    if (moments.x2 == 0 || moments.y2 == 0){ 
      params[4] = 2.0; 
      params[5] = 2.0; 
      params[6] = 0.0; 
    } else { 
      params[4] = 1.0 / shape.sx; 
      params[5] = 1.0 / shape.sy; 
      params[6] = shape.sxy; 
    } 
 
    //    printf("Who is NaN? momx: %4.3f  momy: %4.3f  momxy: %4.3f\n", moments.x2,moments.y2, moments.xy); 
 
    return(true); 
} 
 
//fixed 
bool PM_MODEL_FROM_PSF (pmModel *modelPSF, pmModel *modelFLT, pmPSF *psf)
{
    psF32 *out = modelPSF->params->data.F32; 
    psF32 *in  = modelFLT->params->data.F32; 
     
    out[0] = in[0]; 
    out[1] = in[1]; 
    out[2] = in[2]; 
    out[3] = in[3]; 
    out[7] = in[7]; 
    out[8] = in[8]; 
 
    for (int i = 4; i < 7; i++) { 
      pmTrend2D *trend = psf->params->data[i-4]; 
	out[i] = pmTrend2DEval (trend, out[2], out[3]); 
    } 
    return(true); 
} 
 
// construct the PSF model from the FLT model and the psf
// XXX is this sufficiently general do be a global function, not a pmModelClass function?
bool PM_MODEL_PARAMS_FROM_PSF (pmModel *model, pmPSF *psf, float Xo, float Yo, float Io)
{
    psF32 *PAR = model->params->data.F32;

    // we require these two parameters to exist
    assert (psf->params->n > PM_PAR_YPOS);
    assert (psf->params->n > PM_PAR_XPOS);

    PAR[PM_PAR_SKY]  = 0.0;
    PAR[PM_PAR_I0]   = Io;
    PAR[PM_PAR_XPOS] = Xo;
    PAR[PM_PAR_YPOS] = Yo;
    
    // supply the model-fitted parameters, or copy from the input
    for (int i = 0; i < psf->params->n; i++) {
	if (i == PM_PAR_SKY) continue;
	pmTrend2D *trend = psf->params->data[i];
	PAR[i] = pmTrend2DEval(trend, Xo, Yo);
    }

    // the 2D PSF model fits polarization terms (E0,E1,E2)
    // convert to shape terms (SXX,SYY,SXY)
    // XXX user-defined value for limit?
    if (!pmPSF_FitToModel (PAR, 0.1)) {
	psError(PM_ERR_PSF, false, "Failed to fit object at (r,c) = (%.1f,%.1f)", Xo, Yo);
	return false;
    }

    // apply the model limits here: this truncates excessive extrapolation
    // XXX do we need to do this still?  should we put in asserts to test?
    for (int i = 0; i < psf->params->n; i++) {
        // apply the limits to all components or just the psf-model parameters?
        if (psf->params->data[i] == NULL)
            continue;

	bool status = true;
        status &= PM_MODEL_LIMITS (PS_MINIMIZE_PARAM_MIN, i, PAR, NULL);
        status &= PM_MODEL_LIMITS (PS_MINIMIZE_PARAM_MAX, i, PAR, NULL);
	if (!status) {
	    psTrace ("psModules.objects", 5, "Hitting parameter limits at (r,c) = (%.1f, %.1f)", Xo, Yo);
	    model->flags |= PM_MODEL_STATUS_LIMITS;
	}
    }
    return(true);
}

//done I think 
bool PM_MODEL_FIT_STATUS (pmModel *model)
{
    psF32 dP; 
    bool  status; 
 
    psF32 *PAR  = model->params->data.F32; 
    psF32 *dPAR = model->dparams->data.F32; 
 
    dP = 0; 
    dP += PS_SQR(dPAR[4] / PAR[4]); 
    dP += PS_SQR(dPAR[5] / PAR[5]); 
    dP = sqrt (dP); 
 
    status = true; 
    status &= (dP < 0.5); 
    status &= (PAR[1] > 0); 
    status &= ((dPAR[1]/PAR[1]) < 0.5); 
    //    status &= ((dPAR[7]/PAR[7]) < 0.5); 
    //    status &= ((dPAR[8]/PAR[8]) < 0.5); 
 
    if (status) return true; 
    return false; 
} 

# undef PM_MODEL_FUNC
# undef PM_MODEL_FLUX
# undef PM_MODEL_GUESS
# undef PM_MODEL_LIMITS
# undef PM_MODEL_RADIUS
# undef PM_MODEL_FROM_PSF
# undef PM_MODEL_PARAMS_FROM_PSF
# undef PM_MODEL_FIT_STATUS
