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LCLM

  

find the Least Common Left Multiple of differential operators

 

Calling Sequence

Parameters

Description

Examples

Calling Sequence

LCLM(L1, L2,.., Ln, domain, opt)

Parameters

L1, L2, .., Ln

-

differential operators

domain

-

a list containing two names

opt

-

(optional) arguments

Description

• 

The least common left multiple F=LCLM(L1 .. Ln) of operators L1..Ln is defined as the operator with minimal order such that all solutions L1..Ln are solutions of F as well.

• 

If the optional argument groundfield=ext where ext is a list of RootOfs is given, then LCLM( L1 .. Ln) and all their conjugates over the field Qext is computed. This LCLM is an element of Qext,x Dx.

• 

The quotes for the name groundfield are only necessary if groundfield has been given a value; otherwise they may be omitted.

• 

The argument domain describes the differential algebra. If this argument is the list Dt,t then the differential operators are notated with the symbols Dt and t. They are viewed as elements of the differential algebra Ct Dt where C is the field of constants.

• 

If the argument domain is omitted then the differential specified by the environment variable _Envdiffopdomain will be used. If this environment variable is not set then the argument domain may not be omitted.

• 

This function is part of the DEtools package, and so it can be used in the form LCLM(..) only after executing the command with(DEtools). However, it can always be accessed through the long form of the command by using DEtools[LCLM](..).

Examples

withDEtools:

aRootOfx22

aRootOf_Z22

(1)

bRootOfx23

bRootOf_Z23

(2)

ADx,x

ADx,x

(3)

LLCLMDx+a,Dx2+bDx+x,A:

degreeL,Dx

3

(4)

LLCLMDx+a,Dx2+bDx+x,A,'groundfield'=b:

degreeL,Dx

4

(5)

LLCLMDx+a,Dx2+bDx+x,A,'groundfield'=a:

degreeL,Dx

5

(6)

LLCLMDx+a,Dx2+bDx+x,A,'groundfield'=

LDx65x4+32x3+36x240x13Dx5x5+8x4+12x320x213x8+2x6+11x516x488x3+146x2+161x+24Dx4x5+8x4+12x320x213x83x59x4124x360x2+297x+233Dx3x5+8x4+12x320x213x8+x7+4x614x521x4+87x3248x2214x+65Dx2x5+8x4+12x320x213x8+23x5+x460x3+12x2+217x+207Dxx5+8x4+12x320x213x82x7+8x6+12x521x441x336x2+56x+81x5+8x4+12x320x213x8

(7)

degreeL,Dx

6

(8)

See Also

DEtools[DFactorLCLM]

diffop

Ore_algebra/annihilators