def check_3(self,f=f1,per=0,s=0,a=0,b=2*pi,N=20,xb=None,xe=None,
ia=0,ib=2*pi,dx=0.2*pi):
if xb is None: xb=a
if xe is None: xe=b
x=a+(b-a)*arange(N+1,dtype=float)/float(N) # nodes
v=f(x)
nk=[]
put(" k : Roots of s(x) approx %s x in [%s,%s]:"%\
(f(None),repr(round(a,3)),repr(round(b,3))))
for k in range(1,6):
tck=splrep(x,v,s=s,per=per,k=k,xe=xe)
roots = sproot(tck)
if k == 3:
assert_allclose(roots, pi*array([1, 2, 3, 4]),
rtol=1e-3)
put(' %d : %s'%(k,repr(roots.tolist())))
