+--------------------------------------------------------------------+
| |
| $THETA |
| |
+--------------------------------------------------------------------+
MEANING: Gives initial estimates and bounds for thetas
CONTEXT: NM-TRAN Control Record
USAGE:
$THETA value1 [value2] [value3] ...
[(value)xn]
[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 paren-
theses, 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. With NONMEM 7.4, when initial thetas are
to be estimated, evaluations can now be done for FOCE and
Laplace, not just for FO.
(value)xn
Any initial value or group of initial values may be enclosed in |
parentheses and followed by "xn", which means to replicate the |
values within parentheses n times ("repeated value"). The values |
within the parenthesis may have any of the above forms. For |
example, the following two are equivalent: |
$THETA 2 2 2 2 (0.001,0.1,1000) (0.001,0.1,1000) (0.001,0.1,1000) |
(0.5 FIXED) (0.5 FIXED) |
$THETA (2)x4 (0.001,0.1,1000)x3 (0.5 FIXED)x2 |
NUMBERPOINTS=n
During NONMEM's search for an initial estimate, a number of
points will be examined. This number will be automatically
determined 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 prece-
dence.
REFERENCES: Guide IV Section III.B.9
Go to main index.
Created by nmhelp2html v. 1.0 written by Niclas Jonsson (Modified by AJB 5/2006,11/2007,10/2012)