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   triangular wave (amplitude and phase parameters) signal model.
00010 
00011   File:     model_trnglrwave_ap.c
00012   Author:   B. Douglas Ward
00013   Date:     29 May 1997
00014 */
00015 
00016 
00017 /*---------------------------------------------------------------------------*/
00018 
00019 #include <math.h>
00020 #include "NLfit_model.h"
00021 
00022 void signal_model 
00023 (
00024   float * gs,                /* parameters for signal model */
00025   int ts_length,             /* length of time series data */
00026   float ** x_array,          /* independent variable matrix */
00027   float * ts_array           /* estimated signal model time series */  
00028 );
00029 
00030 
00031 /*---------------------------------------------------------------------------*/
00032 /*
00033   Routine to initialize the signal model by defining the number of parameters
00034   in the signal model, the name of the signal model, and the default values
00035   for the minimum and maximum parameter constraints.
00036 */
00037 
00038 DEFINE_MODEL_PROTOTYPE
00039 
00040 MODEL_interface * initialize_model ()
00041 {
00042   MODEL_interface * mi = NULL;
00043 
00044 
00045   /*----- allocate memory space for model interface -----*/
00046   mi = (MODEL_interface *) XtMalloc (sizeof(MODEL_interface));
00047 
00048 
00049   /*----- define interface for the triangular wave model -----*/   
00050 
00051   /*----- name of this model -----*/
00052   strcpy (mi->label, "TrnglrWave_AP");
00053 
00054   /*----- this is a signal model -----*/
00055   mi->model_type = MODEL_SIGNAL_TYPE;
00056 
00057   /*----- number of parameters in the model -----*/
00058   mi->params = 2;
00059 
00060   /*----- parameter labels -----*/
00061   strcpy (mi->plabel[0], "amplitude");
00062   strcpy (mi->plabel[1], "phase");
00063 
00064   /*----- minimum and maximum parameter constraints -----*/
00065   mi->min_constr[0] =   -100.0;    mi->max_constr[0] =   100.0;
00066   mi->min_constr[1] =    -90.0;    mi->max_constr[1] =     0.00;
00067   
00068   /*----- function which implements the model -----*/
00069   mi->call_func = &signal_model;
00070 
00071 
00072   /*----- return pointer to the model interface -----*/
00073   return (mi);
00074 }
00075 
00076 
00077 /*---------------------------------------------------------------------------*/
00078 /*
00079   Routine to calculate the time series which results from using the
00080   triangular wave model with specified amplitude and phase parameters.
00081 
00082   Definition of model parameters:
00083 
00084         gs[0] = amplitude of triangular wave
00085         gs[1] = phase angle of triangular wave (degrees)
00086 */
00087 
00088 void signal_model 
00089 (
00090   float * gs,                /* parameters for signal model */
00091   int ts_length,             /* length of time series data */
00092   float ** x_array,          /* independent variable matrix */
00093   float * ts_array           /* estimated signal model time series */  
00094 )
00095 
00096 {
00097   const float FREQ = 0.125;         /* frequency of the triangular wave */
00098   int it;                           /* time index */     
00099   float t;                          /* time */
00100   float fval;                       /* time series value at time t */  
00101   float cycles;                     /* number of cycles since initial time */
00102 
00103 
00104   /*----- calculate time series corresponding to the given parameters -----*/
00105   for (it = 0;  it < ts_length;  it++)
00106     { 
00107       t = x_array[it][1];
00108       cycles = FREQ*t + gs[1]/360.0;
00109       cycles = cycles - (int)cycles;
00110       if (cycles <= 0.25)
00111         fval = gs[0] * (cycles/0.25);
00112       else
00113         if ((cycles > 0.25) && (cycles <= 0.75))
00114           fval = gs[0] * (2.0 - (cycles/0.25));
00115         else
00116           fval = gs[0] * ((cycles/0.25) - 4.0);
00117       ts_array[it] = fval;      
00118     }
00119   
00120 }
00121 
00122 
00123 
00124