Class min_base (o2scl)¶
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template<class
func_t
= funct, classdfunc_t
= func_t>
classo2scl
::
min_base
¶ One-dimensional minimization [abstract base].
Public Functions
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min_base
()¶
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~min_base
()¶
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int
print_iter
(double x, double y, int iter, double value = 0.0, double limit = 0.0, std::string comment = "")¶ Print out iteration information.
Depending on the value of the variable verbose, this prints out the iteration information. If verbose=0, then no information is printed, while if verbose>1, then after each iteration, the present values of x and y are output to std::cout along with the iteration number. If verbose>=2 then each iteration waits for a character.
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int
min
(double &x, double &fmin, func_t &func) = 0¶ Calculate the minimum
min
offunc
w.r.t ‘x’.If this is not overloaded, it attempts to bracket the minimum using bracket() and then calls min_bkt() with the newly bracketed minimum.
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int
min_bkt
(double &x2, double x1, double x3, double &fmin, func_t &func) = 0¶ Calculate the minimum
min
offunc
with x2 bracketed between x1 and x3.If this is not overloaded, it ignores the bracket and calls min().
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int
min_de
(double &x, double &fmin, func_t &func, dfunc_t &df) = 0¶ Calculate the minimum
min
offunc
with derivativedfunc
w.r.t ‘x’.If this is not overloaded, it attempts to bracket the minimum using bracket() and then calls min_bkt_de() with the newly bracketed minimum.
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int
bracket
(double &ax, double &bx, double &cx, double &fa, double &fb, double &fc, func_t &func)¶ Given interval
(ax,bx)
, attempt to bracket a minimum for functionfunc
.Upon success,
fa=func(ax)
,fb=func(bx)
, andfc=func(cx)
withfb<fa
,fb<fc
andax<bx<cx
. The initial values ofcx
,fa
,fb
, andfc
are all ignored.The number of iterations is controlled by bracket_iter.
- Idea for Future:
Improve this algorithm with the golden ratio method in gsl/min/bracketing.c?
- Note
This algorithm can fail if there’s a minimum which has a much smaller size than \( bx-ax \), or if the function has the same value at
ax
,bx
, and the midpoint(ax+bx)/2
.
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const char *
type
()¶ Return string denoting type (“min”)
Public Members
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int
verbose
¶ Output control.
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int
ntrial
¶ Maximum number of iterations.
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double
tol_rel
¶ The tolerance for the minimum function value.
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double
tol_abs
¶ The tolerance for the location of the minimum.
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int
last_ntrial
¶ The number of iterations used in the most recent minimization.
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int
bracket_iter
¶ The number of iterations for automatically bracketing a minimum (default 20)
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bool
err_nonconv
¶ If true, call the error handler if the routine does not “converge”.
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