include/gmx_statistics.h

   1 /*
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  34
  35 #ifndef _GMX_STATS_H
  36 #define _GMX_STATS_H
  37
  38 #ifdef __cplusplus
  39 extern "C" {
  40 #endif
  41
  42 #include "typedefs.h"
  43
  44 typedef struct gmx_stats *gmx_stats_t;
  45
  46 /* Error codes returned by the routines */
  47 enum { estatsOK, estatsNO_POINTS, estatsNO_MEMORY, estatsERROR,
  48        estatsINVALID_INPUT, estatsNOT_IMPLEMENTED, estatsNR };
  49
  50 enum { elsqWEIGHT_NONE, elsqWEIGHT_X, elsqWEIGHT_Y,
  51        elsqWEIGHT_XY, elsqWEIGHT_NR  };
  52
  53 enum { ehistoX, ehistoY, ehistoNR };
  54
  55 gmx_stats_t gmx_stats_init();
  56
  57 int gmx_stats_done(gmx_stats_t stats);
  58
  59 /* Remove outliers from a straight line, where level in units of
  60    sigma. Level needs to be larger than one obviously. */
  61 int gmx_stats_remove_outliers(gmx_stats_t stats,double level);
  62
  63 int gmx_stats_add_point(gmx_stats_t stats,double x,double y,
  64                                double dx,double dy);
  65
  66 /* The arrays dx and dy may be NULL if no uncertainties are available,
  67    in that case zero uncertainties will be assumed. */
  68 int gmx_stats_add_points(gmx_stats_t stats,int n,real *x,real *y,
  69                                 real *dx,real *dy);
  70
  71 /* Return the data points one by one. Return estatsOK while there are
  72    more points, and returns estatsNOPOINTS when the last point has
  73    been returned. Should be used in a while loop. Variables for either
  74    pointer may be NULL, in which case the routine can be used as an
  75    expensive point counter. */
  76 int gmx_stats_get_point(gmx_stats_t stats,real *x,real *y,
  77                                real *dx,real *dy);
  78
  79 /* Fit the data to y = ax + b, possibly weighted, if uncertainties
  80    have been input. Returns slope in *a and intercept in b, *return
  81    sigmas in *da and *db respectively. Returns normalized *quality of
  82    fit in *chi2 and correlation of fit with data in Rfit. chi2, Rfit,
  83    da and db may be NULL. */
  84 int gmx_stats_get_ab(gmx_stats_t stats,int weight,
  85                             real *a,real *b,
  86                             real *da,real *db,real *chi2,real *Rfit);
  87
  88 /* Fit the data to y = ax, possibly weighted, if uncertainties have
  89    been input. Returns slope in *a, sigma in a in *da, and normalized
  90    quality of fit in *chi2 and correlation of fit with data in
  91    Rfit. chi2, Rfit and da may be NULL. */
  92 int gmx_stats_get_a(gmx_stats_t stats,int weight,
  93                            real *a,real *da,real *chi2,real *Rfit);
  94
  95 /* Return the correlation coefficient between the data (x and y) as
  96    input to the structure. */
  97 int gmx_stats_get_corr_coeff(gmx_stats_t stats,real *R);
  98
  99 /* Returns the root mean square deviation between x and y values. */
 100 int gmx_stats_get_rmsd(gmx_stats_t gstats,real *rmsd);
 101
 102 int gmx_stats_get_npoints(gmx_stats_t stats,int *N);
 103
 104 int gmx_stats_get_average(gmx_stats_t stats,real *aver);
 105
 106 int gmx_stats_get_sigma(gmx_stats_t stats,real *sigma);
 107
 108 int gmx_stats_get_error(gmx_stats_t stats,real *error);
 109
 110 /* Get all three of the above. Pointers may be null, in which case no
 111    assignment will be done. */
 112 int gmx_stats_get_ase(gmx_stats_t gstats,real *aver,real *sigma,real *error);
 113
 114 /* Dump the x, y, dx, dy data to a text file */
 115 int gmx_stats_dump_xy(gmx_stats_t gstats,FILE *fp);
 116
 117 /* Make a histogram of the data present. Uses either bindwith to
 118    determine the number of bins, or nbins to determine the binwidth,
 119    therefore one of these should be zero, but not the other. If *nbins = 0
 120    the number of bins will be returned in this variable. ehisto should be one of
 121    ehistoX or ehistoY. If
 122    normalized not equal to zero, the integral of the histogram will be
 123    normalized to one. The output is in two arrays, *x and *y, to which
 124    you should pass a pointer. Memory for the arrays will be allocated
 125    as needed. Function returns one of the estats codes. */
 126 int gmx_stats_make_histogram(gmx_stats_t gstats,real binwidth,int *nbins,
 127                                     int ehisto,
 128                                     int normalized,real **x,real **y);
 129
 130 /* Return message belonging to error code */
 131 const char *gmx_stats_message(int estats);
 132
 133 /****************************************************
 134  * Some statistics utilities for convenience: useful when a complete data
 135  * set is available already from another source, e.g. an xvg file.
 136  ****************************************************/
 137 int lsq_y_ax(int n, real x[], real y[], real *a);
 138 /* Fit a straight line y=ax thru the n data points x, y, return the
 139    slope in *a. Return value can be estatsOK, or something else. */
 140
 141 int lsq_y_ax_b(int n, real x[], real y[], real *a, real *b,real *r,
 142                       real *chi2);
 143 /* Fit a straight line y=ax+b thru the n data points x,y.
 144  * Returns the "fit quality" sigma = sqrt(chi^2/(n-2)).
 145  * The correlation coefficient is returned in r.
 146  */
 147
 148 int lsq_y_ax_b_xdouble(int n, double x[], real y[],
 149                                real *a, real *b,real *r,real *chi2);
 150 /* As lsq_y_ax_b, but with x in double precision.
 151  */
 152
 153 int lsq_y_ax_b_error(int n, real x[], real y[], real dy[],
 154                              real *a, real *b, real *da, real *db,
 155                              real *r,real *chi2);
 156 /* Fit a straight line y=ax+b thru the n data points x,y, with sigma dy
 157  * Returns the "fit quality" sigma = sqrt(chi^2/(n-2)).
 158  * The correlation coefficient is returned in r.
 159  */
 160
 161 #ifdef __cplusplus
 162 }
 163 #endif
 164
 165 #endif