//MomentTensor returns the moment tensor for a matrix A of coordinates and a column
//vector mass with the respective massess.
func MomentTensor(A *v3.Matrix, massslice []float64) (*v3.Matrix, error) {
ar, ac := A.Dims()
var err error
var mass *mat64.Dense
if massslice == nil {
mass = gnOnes(ar, 1)
} else {
mass = mat64.NewDense(ar, 1, massslice)
// if err != nil {
// return nil, err
// }
}
center, _, err := MassCenter(A, v3.Dense2Matrix(gnCopy(A)), mass)
if err != nil {
return nil, errDecorate(err, "MomentTensor")
}
sqrmass := gnZeros(ar, 1)
// sqrmass.Pow(mass,0.5)
pow(mass, sqrmass, 0.5) //the result is stored in sqrmass
// fmt.Println(center,sqrmass) ////////////////////////
center.ScaleByCol(center, sqrmass)
// fmt.Println(center,"scaled center")
centerT := gnZeros(ac, ar)
centerT.Copy(center.T())
moment := gnMul(centerT, center)
return v3.Dense2Matrix(moment), nil
}
//OnesMass returns a column matrix with lenght rosw.
//This matrix can be used as a dummy mass matrix
//for geometric calculations.
func OnesMass(lenght int) *v3.Matrix {
return v3.Dense2Matrix(gnOnes(lenght, 1))
}