00001 /*****************************************************************************
00002    Major portions of this software are copyrighted by the Medical College
00003    of Wisconsin, 1994-2000, and are released under the Gnu General Public
00004    License, Version 2.  See the file README.Copyright for details.
00005 ******************************************************************************/
00006    
00007 /*
00008   This file contains routines to initialize and implement the
00009   linear trend noise model.
00010 
00011   File:     model_linear.c
00012   Author:   B. Douglas Ward
00013   Date:     29 May 1997
00014 
00015 */
00016 
00017 
00018 /*---------------------------------------------------------------------------*/
00019 
00020 #include <math.h>
00021 #include "NLfit_model.h"
00022 
00023 
00024 void noise_model 
00025 (
00026   float * gn,                /* parameters for noise model */
00027   int ts_length,             /* length of time series data */
00028   float ** x_array,          /* independent variable matrix */
00029   float * ts_array           /* estimated noise model time series */  
00030 );
00031 
00032 
00033 /*---------------------------------------------------------------------------*/
00034 /*
00035   Routine to initialize the noise model by defining the number of parameters
00036   in the noise model, the name of the noise model, and the default values
00037   for the minimum and maximum parameter constraints.
00038 */
00039 
00040 DEFINE_MODEL_PROTOTYPE
00041 
00042 MODEL_interface * initialize_model ()
00043 {
00044   MODEL_interface * mi = NULL;
00045 
00046 
00047   /*----- allocate memory space for model interface -----*/
00048   mi = (MODEL_interface *) XtMalloc (sizeof(MODEL_interface));
00049 
00050 
00051   /*----- define linear plus noise model -----*/   
00052 
00053   /*----- name of this model -----*/
00054   strcpy (mi->label, "Linear");
00055 
00056   /*----- this is a noise model -----*/
00057   mi->model_type = MODEL_NOISE_TYPE;
00058 
00059   /*----- number of parameters in the model -----*/
00060   mi->params = 2;
00061 
00062   /*----- parameter labels -----*/
00063   strcpy (mi->plabel[0], "constant");
00064   strcpy (mi->plabel[1], "linear");
00065 
00066   /*----- minimum and maximum parameter constraints -----*/
00067   mi->min_constr[0] = -100.0;   mi->max_constr[0] = 100.0;
00068   mi->min_constr[1] =   -1.0;   mi->max_constr[1] =   1.0;
00069   
00070   /*----- function which implements the model -----*/
00071   mi->call_func = noise_model;
00072 
00073 
00074   /*----- return pointer to the model interface -----*/
00075   return (mi);
00076 }
00077 
00078 
00079 /*---------------------------------------------------------------------------*/
00080 /*
00081   Routine to calculate the time series which results from the linear trend
00082   noise model and model parameters.
00083 
00084   Definition of model parameters:
00085 
00086      gn[0] = constant coefficient
00087      gn[1] = linear coefficient
00088 */
00089 
00090 void noise_model 
00091 (
00092   float * gn,                /* parameters for noise model */
00093   int ts_length,             /* length of time series data */
00094   float ** x_array,          /* independent variable matrix */
00095   float * ts_array           /* estimated noise model time series */  
00096 )
00097 
00098 {
00099   int it;                           /* time index */     
00100   float t;                          /* time */
00101   float fval;                       /* time series value at time t */  
00102 
00103 
00104   for (it = 0;  it < ts_length;  it++)
00105     {
00106       t = x_array[it][1];
00107       fval = gn[0] + gn[1]*t;
00108       ts_array[it] = fval;
00109     }
00110   
00111 }
00112