include/gmx_statistics.h

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