m.svfit(1)	       Grass User's Manual	       m.svfit(1)



NNAAMMEE
       _m_._s_v_f_i_t - Semivariogram model fitting.
       _(_G_R_A_S_S _D_a_t_a _I_m_p_o_r_t_/_P_r_o_c_e_s_s_i_n_g _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       mm..ssvvffiitt
       mm..ssvvffiitt hheellpp
       mm..ssvvffiitt	 [--ppqqww]   [iinnppuutt==_n_a_m_e]	 mmooddeell==_v_a_l_u_e  rraannggee==_v_a_l_u_e
       [ggrraapphh==_n_a_m_e]

DDEESSCCRRIIPPTTIIOONN
       _m_._s_v_f_i_t calculates a sample semivariogram and either plots
       it  using  _g_n_u_p_l_o_t  or  writes the estimated parameters to
       standard output, or both.


       For more information, refer to the  tutorial  or  see  the
       example below.



OOPPTTIIOONNSS
   FFllaaggss::
       --qq     Quiet. Cut out the chatter.

       --pp     Plot  model and sample semivariogram (requires _g_n_u_-
	      _p_l_o_t).

       --ww     Use weighted  least  squares  (default  is  general
	      least squares)


   PPaarraammeetteerrss::
       ssiitteess==_n_a_m_e
	      UNIX  file  containing  sample  semivariogram  (see
	      NOTES).  Default is standard input.

       mmooddeell==_v_a_l_u_e
	      Integer Model Index, one of

	       Linear,

	       Spherical,

	       Exponential,

	       Gaussian,

	       Quadratic, or

	       Wave or Hole Effect.


       rraannggee==_v_a_l_u_e
	      Range of semivariogram.

       ggrraapphh==_n_a_m_e
	      Basename	to  save  graphing  data/commands  files.
	      Graphs  are  saved in the current working directory
	      with the extensions .gp and .dat.  Implies  the  --pp
	      flag.


NNOOTTEESS
       Three  columns of data are expected as input: lag distance
       (_h), semivariogram value (_g_a_m_m_a), and the number  of  data
       pairs  used to compute it (_N_(_h_)).  This may either be from
       a UNIX file, entered from the command line (terminated  by
       control-d), or via a pipe or redirection.


       The  plotting program can be selected by setting the envi-
       ronment variable GGRRAASSSS__GGNNUUPPLLOOTT .

EEXXAAMMPPLLEE
       _m_._s_v_f_i_t was designed to be used in conjunction with  _s_._s_v,
       a  GRASS  sites	program  for calculating sample semivari-
       ograms. The following example calculates a sample semivar-
       iogram of the sites list _w_e_l_l_s with a nominal lag distance
       of 5 and then fits a linear model with  a  range  of  100.
       The  sample semivariogram and model are plotted using _g_n_u_-
       _p_l_o_t and the graphing instructions and data are	saved  to
       files  with  the  basename  _s_v_w_e_l_l_s in the current working
       directory: ss..ssvv --qq _w_e_l_l_s llaagg==_5  |  mm..ssvvffiitt  --pp  mm==_1  rr==_1_0_0
       gg==_s_v_w_e_l_l_s

       By saving the graphing instructions and data, the semivar-
       iogram may be plotted again later by  the  following  com-
       mand: ggnnuupplloott _s_v_w_e_l_l_s_._g_p


SSEEEE AALLSSOO
       _s_._u_n_i_v_a_r, _s_._n_o_r_m_a_l, _s_._s_v _g_n_u_p_l_o_t and


       _S_e_m_i_v_a_r_i_o_g_r_a_m  _M_o_d_e_l_i_n_g	- A GRASS Tutorial on Exploratory
       Data Analysis and Semivariogram Modeling.

BBUUGGSS
       Please send all bug fixes and comments to the author.

AAUUTTHHOORR
       James Darrell McCauley, Agricultural  Engineering,  Purdue
       University

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_3 _$



GRASS 5.0					       m.svfit(1)
