# Singular

#### D.15.10.13 setinitials

Procedure from library `finitediff.lib` (see finitediff_lib).

Usage:
setinitials(V,D[,P]); V,D,P are lists with strings as elements

Return:
no return value: sets the dependence order of the occuring derivatives, constructs the suitable ring to compute in containing user chosen parameters, sets new basering

Note:
P is optional, used to introduce some additional parameters into the ring. The Sine and Cosine values needed for the fourier transformation are symbolically introduced under the names string(c)+nameof(variable), i.e. if x is any spatial variable then cx:=cosine(dx*ksi), when regarding the fourier transform after ksi (for sine respectively). Artificial parameters I,T,Px,Py are introduced for the later eigenvalue analysis. Variables can be transformed into parameters of similar name

Example:
 ```LIB "finitediff.lib"; list D="Ut","Ux","Uy","U"; list V="t","x","y"; list P="alpha","beta","gamma"; setinitials(V,D,P);////does not show the ring, since there is no output basering;///does show the ring ==> // characteristic : 0 ==> // 14 parameter : I T Px Py Cx Cy Sx Sy alpha beta gamma dt dx dy ==> // minpoly : 0 ==> // number of vars : 8 ==> // block 1 : ordering c ==> // block 2 : ordering lp ==> // : names i t x y cx cy sx sy ==> // quotient ring from ideal ==> _[1]=cy^2+sy^2-1 ==> _[2]=cx^2+sx^2-1 ==> _[3]=i^2+1 ```