#8501: find_root evaluates by plugging an equation into the function
-------------------------+--------------------------------------------------
Reporter: jason | Owner: jkantor
Type: defect | Status: new
Priority: major | Milestone: sage-4.3.4
Component: numerical | Keywords:
Author: | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
-------------------------+--------------------------------------------------
With 4.3.3:
{{{
sage: f1=0.6*x
sage: f2=0.045*x^2 - 1.44*x + 8.64
sage: def k(x):
... print x
... if 5<=x<=8:
... return f1(x=x)
... elif 8<=x<=13:
... return f2(x=x)
... else:
... raise ValueError, "Called with impossible value: %s"%x
...
sage: find_root(lambda x:k(x)-55,5,10)
5.0
10.0
6.90983005625
8.09016994375
6.1803398875
6.63093253165711 == 6.68257664471270
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "_sage_input_198.py", line 9, in <module>
exec compile(ur'open("___code___.py","w").write("# -*- coding: utf-8
-*-\n" +
_support_.preparse_worksheet_cell(base64.b64decode("ZmluZF9yb290KGxhbWJkYSB4OmsoeCktNTUsNSwxMCk="),globals())+"\n");
execfile(os.path.abspath("___code___.py"))' + '\n', '', 'single')
File "", line 1, in <module>
File "/tmp/tmp1LUqkk/___code___.py", line 3, in <module>
exec compile(ur'find_root(lambda x:k(x)-_sage_const_55 ,_sage_const_5
,_sage_const_10 )' + '\n', '', 'single')
File "", line 1, in <module>
File "/home/grout/sage/local/lib/python2.6/site-
packages/sage/numerical/optimize.py", line 92, in find_root
val, s = find_maximum_on_interval(f, a, b)
File "/home/grout/sage/local/lib/python2.6/site-
packages/sage/numerical/optimize.py", line 122, in
find_maximum_on_interval
minval, x = find_minimum_on_interval(lambda z: -f(z), a=a, b=b,
tol=tol, maxfun=maxfun)
File "/home/grout/sage/local/lib/python2.6/site-
packages/sage/numerical/optimize.py", line 181, in
find_minimum_on_interval
xmin, fval, iter, funcalls = scipy.optimize.fminbound(f, a, b,
full_output=1, xtol=tol, maxfun=maxfun)
File "/home/grout/sage/local/lib/python2.6/site-
packages/scipy/optimize/optimize.py", line 1256, in fminbound
fu = func(x,*args)
File "/home/grout/sage/local/lib/python2.6/site-
packages/sage/numerical/optimize.py", line 122, in <lambda>
minval, x = find_minimum_on_interval(lambda z: -f(z), a=a, b=b,
tol=tol, maxfun=maxfun)
File "", line 1, in <lambda>
File "/tmp/tmpzDC3MH/___code___.py", line 12, in k
raise ValueError, "Called with impossible value: %s"%x
ValueError: Called with impossible value: 6.63093253165711 ==
6.68257664471270
}}}
Note that the last evaluation was a symbolic equation, something ==
something. That of course breaks the function.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/8501>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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