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 |                                $THETA                           |
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 MEANING: Gives initial estimates and bounds for thetas
 CONTEXT: NM-TRAN Control Record

 USAGE:
 $THETA  value1  [value2]  [value3] ...
         [NUMBERPOINTS=n]
         [ABORT|NOABORT|NOABORTFIRST]

 SAMPLE:
 $THETA  (0,3) 2 FIXED (0,.6,1) 10 (-INF,-2.7,0) (37 FIXED)

 DISCUSSION:
 Gives initial estimates and bounds for elements of the  THETA  matrix.
 Thetas are numbered in the order in which they are defined.

 OPTIONS:

 Each value defines a theta and gives its initial estimate and  bounds.
 A value has one of 4 forms:

 init [FIXED]
      Init is the initial estimate.  If FIXED is used, the final param-
      eter estimate is to be constrained to equal the initial parameter
      estimate.

 ([low,] init [,up] [FIXED])
      Low and up are lower and upper bounds respectively.  They are the
      boundaries for the minimization search.  Commas are optional.  If
      an upper bound is used, a lower bound must also  be  used  (e.g.,
      -INF;  see  below).   The  lower and upper bounds (or if just the
      lower bound is used, then just this bound)  may  be  omitted,  in
      which case this form differs from the one described above only in
      so far as with this form, the  initial  estimate  and  the  FIXED
      attribute are enclosed in parentheses.  When FIXED is used, and a
      bound appears the bound must equal the initial  estimate.   FIXED
      is  implied when all three values are equal.  The lower bound can
      be -INF (i.e., -infinity), and the upper bound can be INF  (i.e.,
      +infinity).  These  are  the defaults for lower and upper bounds.
      They are communicated to NONMEM as numeric  values  -1000000  and
      1000000.

 ([low,] init [,up]) [FIXED]
      This is just like the form described above  except  that  if  the
      FIXED  attribute  is  used,  the  attribute  occurs  outside  the
      parentheses, and then if moreover, a  bound  appears,  the  bound
      need not equal the initial estimate.

 (low,,up)
      The commas are required.  Because no initial estimate is given, a
      search  for  an  initial estimate (the Initial Estimates Step) is
      undertaken by NONMEM.

 NUMBERPOINTS=n
      During NONMEM's search for  an  initial  estimate,  a  number  of
      points will be examined. This number will be automatically deter-
      mined by NONMEM, or it can be specified with  this  option.   May
      also be coded NUMBERPTS, NUMPOINTS, NUMPTS.

 ABORT
      During the Initial Estimates step, NONMEM is to abort  when  PRED
      sets  the  error return code to 1.  (The PRED error return code n
      is set by the statement "EXIT n [k]" in abbreviated code,  or  by
      the  statement  IERPRD=n in user-supplied code, or by PREDPP when
      it detects an error.)  This is the default.

 NOABORT
      During the Initial Estimates step, NONMEM  is  simply  to  ignore
      values  of the theta vector that result in PRED error return code
      1.  (Ordinarily the first value of  the  theta  vector  is  never
      ignored.)  These will not be feasible values for an initial esti-
      mate.

 NOABORTFIRST
      Same as NOABORT option, but also applies to the  first  value  of
      the  theta  vector  that  is  tried.  It cannot be shortened; all
      characters must be coded.  May be used with the  NOABORT  option,
      in  which  case  the stronger condition (NOABORTFIRST) takes pre-
      cedence.

REFERENCES: Guide IV Section III.B.9


  
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