# Singular          #### D.15.12.35 derivationConstructor

Procedure from library `difform.lib` (see difform_lib).

Usage:
derivation phi = inp; inp of any type

Return:
the derivation defined by inp:

Remarks:
the output depens on the type of inp:
- if inp is of type list, the constructor derivationFromList is used - if inp is of type poly, number, int or bigint, derivationFromPoly is used

Note:
for other than the mentioned types, there is no output

Example:
 ```LIB "difform.lib"; ring R = 31,(x,y,z),dp; diffAlgebra(); ==> // The differential algebra Omega_R was constructed and the differential \ forms dx, dy, dz are available. //////////////////////////////////////////////////////////// // Construction of derivations from lists and polynomials // //////////////////////////////////////////////////////////// list L; L = list(dx,dz,dy); L = list(x2,y-x,z); derivation phi = L; phi; ==> Omega_R^1 --> R ==> dx |--> x2 ==> dy |--> z ==> dz |--> -x+y ==> ==> derivation psi = 3x2-12z; psi; ==> Omega_R^1 --> R ==> dx |--> 3x2-12z ==> dy |--> 3x2-12z ==> dz |--> 3x2-12z ==> ==> kill Omega_R,dx,dy,dz,phi,psi; ``` 