// NumericalDeriv computes a particular derivative dN[i]dt @ t using numerical differentiation
// Note: it uses RecursiveBasis and therefore is highly non-efficient
func (o *Bspline) NumericalDeriv(t float64, i int) float64 {
// check
if t < o.tmin || t > o.tmax {
chk.Panic("t must be within [%g, %g]. t=%g is incorrect", t, o.tmin, o.tmax)
}
// derivatives
f := func(x float64, args ...interface{}) float64 {
return o.RecursiveBasis(x, i)
}
return num.DerivRange(f, t, o.tmin, o.tmax)
}
// NumericalDeriv computes a particular derivative dN[i]dt @ t using numerical differentiation
// Note: it uses RecursiveBasis and therefore is highly non-efficient
func (o *Bspline) NumericalDeriv(t float64, i int) float64 {
// check
if t < o.tmin || t > o.tmax {
chk.Panic(_bspline_err02, "NumericalDeriv", t, o.tmin, o.tmax)
}
// derivatives
f := func(x float64, args ...interface{}) float64 {
return o.RecursiveBasis(x, i)
}
return num.DerivRange(f, t, o.tmin, o.tmax)
}
// NumericalDeriv computes a particular derivative dR[i][j][k]du @ t using numerical differentiation
// Note: it uses RecursiveBasis and therefore is highly non-efficient
func (o *Nurbs) NumericalDeriv(dRdu []float64, u []float64, l int) {
var tmp float64
for d := 0; d < o.gnd; d++ {
f := func(x float64, args ...interface{}) (val float64) {
if x < o.b[d].tmin || x > o.b[d].tmax {
chk.Panic("problem with numerical derivative: x=%v is invalid. xrange=[%v,%v]", x, o.b[d].tmin, o.b[d].tmax)
}
tmp = u[d]
u[d] = x
val = o.RecursiveBasis(u, l)
u[d] = tmp
return
}
dRdu[d] = num.DerivRange(f, u[d], o.b[d].tmin, o.b[d].tmax)
}
return
}
// NumericalDeriv computes a particular derivative dR[i][j][k]du @ t using numerical differentiation
// Note: it uses RecursiveBasis and therefore is highly non-efficient
func (o *Nurbs) NumericalDeriv(dRdu []float64, u []float64, l int) {
var tmp float64
for d := 0; d < o.gnd; d++ {
f := func(x float64, args ...interface{}) (val float64) {
if x < o.b[d].tmin || x > o.b[d].tmax {
chk.Panic(_nurbs_err6, x, o.b[d].tmin, o.b[d].tmax)
}
tmp = u[d]
u[d] = x
val = o.RecursiveBasis(u, l)
u[d] = tmp
return
}
dRdu[d] = num.DerivRange(f, u[d], o.b[d].tmin, o.b[d].tmax)
}
return
}
