sin(x)/x minimum search

from FuncDesigner import *
x = oovar()
f = sin(x) / x

S = 10000000
cons1 = [x>=0, x<=S]
cons2 = [x>=-S, x<=0]
cons3 = [x>=-S, x<=S]
startPoint = {x:0.1}
for cons in [cons1, cons2, cons3]:
    S = oosystem()
    r = S.minimize(f, startPoint, solver='interalg', fTol = 0.000000001, constraints = cons, iprint = 0)
    print('minimum value %e  at point %e' %(r.ff, r(x)))
# minimum value -2.172336e-01  at point 4.493409e+00 , 1.38 sec
# minimum value -2.172336e-01  at point -4.493409e+00, 3.27 sec
# minimum value -2.172336e-01  at point -4.493409e+00, 4.78 sec

from numpy import linspace, argmin
xx = linspace(-40, 40, 100000)
y = f({x:xx})
print('minimal value: % 0.7f' % min(y)) # minimal value: -0.2172336
print('best point: % 0.7f' % xx[argmin(y)]) # best point: -4.4932449 (same to +4.4932449)
from pylab import plot, show, grid
plot(xx, y)
grid('on')
show()


------------------------- OpenOpt 0.37 -------------------------
solver: interalg   problem: unnamed    type: NLP   goal: minimum
 iter   objFunVal
    0  9.983e-01
OpenOpt info: Solution with required tolerance 1.0e-09
 is guarantied (obtained precision: 1.0e-09)
  104  -2.172e-01
istop: 1000 (solution has been obtained)
Solver:   Time Elapsed = 1.39   CPU Time Elapsed = 1.38
objFunValue: -0.21723363 (feasible, MaxResidual = 0)
minimum value -2.172336e-01  at point 4.493409e+00

------------------------- OpenOpt 0.37 -------------------------
solver: interalg   problem: unnamed    type: NLP   goal: minimum
 iter   objFunVal
    0  9.983e-01
OpenOpt info: Solution with required tolerance 1.0e-09
 is guarantied (obtained precision: 1.0e-09)
  562  -2.172e-01
istop: 1000 (solution has been obtained)
Solver:   Time Elapsed = 3.45   CPU Time Elapsed = 3.27
objFunValue: -0.21723363 (feasible, MaxResidual = 0)
minimum value -2.172336e-01  at point -4.493409e+00

------------------------- OpenOpt 0.37 -------------------------
solver: interalg   problem: unnamed    type: NLP   goal: minimum
 iter   objFunVal
    0  9.983e-01
OpenOpt info: Solution with required tolerance 1.0e-09
 is guarantied (obtained precision: 1.0e-09)
  563  -2.172e-01
istop: 1000 (solution has been obtained)
Solver:   Time Elapsed = 4.78   CPU Time Elapsed = 4.78
objFunValue: -0.21723363 (feasible, MaxResidual = 0)
minimum value -2.172336e-01  at point -4.493409e+00