bertiniParameterHomotopy -- a main method to perform a parameter homotopy in Bertini

Synopsis

Usage:

S = bertiniParameterHomotopy(F,P,T)
Inputs:
- F, a list, a list of polynomials
- P, a list, a list of parameter indeterminants
- T, a list, a list of lists of target parameter values
Optional inputs:
- AffVariableGroup => ..., default value {}, an option to group variables and use multihomogeneous homotopies
- B'Constants => ..., default value {}, an option to designate the constants for a Bertini Input file
- B'Functions (missing documentation) => ..., default value {},
- BertiniInputConfiguration (missing documentation) => ..., default value {},
- HomVariableGroup => ..., default value {}, an option to group variables and use multihomogeneous homotopies
- M2Precision (missing documentation) => ..., default value 53,
- OutputStyle (missing documentation) => ..., default value "OutPoints",
- RandomComplex => ..., default value {}, an option which designates symbols/strings/variables that will be set to be a random real number or random complex number
- RandomReal => ..., default value {}, an option which designates symbols/strings/variables that will be set to be a random real number or random complex number
- TopDirectory => ..., default value "/tmp/M2-873369-0/0", Option to change directory for file storage.
- Verbose => ..., default value false, Option to silence additional output
Outputs:
- S, a list, a list whose entries are lists of solutions for each target system

Description

This method numerically solves several polynomial systems from a parameterized family at once. The list F is a system of polynomials in ring variables and the parameters listed in P. The list T is the set of parameter values for which solutions to F are desired. Both stages of Bertini's parameter homotopy method are called with bertiniParameterHomotopy. First, Bertini assigns a random complex number to each parameter and solves the resulting system, then, after this initial phase, Bertini computes solutions for every given choice of parameters using a number of paths equal to the exact root count in the first stage.

i1 : R=CC[u1,u2,u3,x,y];

i2 : f1=u1*(y-1)+u2*(y-2)+u3*(y-3); --parameters are u1, u2, and u3

i3 : f2=(x-11)*(x-12)*(x-13)-u1;

i4 : paramValues0={1,0,0};

i5 : paramValues1={0,1+2*ii,0};

i6 : bPH=bertiniParameterHomotopy( {f1,f2}, {u1,u2,u3},{paramValues0 ,paramValues1 })

o6 = {{{11.3376-.56228*ii, 1}, {11.3376+.56228*ii, 1}, {13.3247, 1}}, {{11,
     ------------------------------------------------------------------------
     2}, {12, 2}, {13, 2}}}

o6 : List

i7 : bPH_0--the solutions to the system with parameters set equal to paramValues0

o7 = {{11.3376-.56228*ii, 1}, {11.3376+.56228*ii, 1}, {13.3247, 1}}

o7 : List

i8 : R=CC[x,y,z,u1,u2]

o8 = R

o8 : PolynomialRing

i9 : f1=x^2+y^2-z^2

      2    2    2
o9 = x  + y  - z

o9 : R

i10 : f2=u1*x+u2*y

o10 = x*u1 + y*u2

o10 : R

i11 : finalParameters0={0,1}

o11 = {0, 1}

o11 : List

i12 : finalParameters1={1,0}

o12 = {1, 0}

o12 : List

i13 : bPH=bertiniParameterHomotopy( {f1,f2}, {u1,u2},{finalParameters0 ,finalParameters1 },HomVariableGroup=>{x,y,z})

o13 = {{{1, 1.04634e-17-1.01448e-17*ii, -1}, {1, 1.32111e-17+6.418e-20*ii,
      -----------------------------------------------------------------------
      1}}, {{9.97833e-19+1.09185e-18*ii, 1, 1}, {-5.41884e-16+1.41201e-16*ii,
      -----------------------------------------------------------------------
      1, -1}}}

o13 : List

i14 : bPH_0--The two solutions for finalParameters0

o14 = {{1, 1.04634e-17-1.01448e-17*ii, -1}, {1, 1.32111e-17+6.418e-20*ii, 1}}

o14 : List

i15 : finParamValues={{1},{2}}

o15 = {{1}, {2}}

o15 : List

i16 : bPH1=bertiniParameterHomotopy( {"x^2-u1"}, {u1},finParamValues,AffVariableGroup=>{x})

o16 = {{{-1}, {1}}, {{-1.41421}, {1.41421}}}

o16 : List

i17 : bPH2=bertiniParameterHomotopy( {"x^2-u1"}, {u1},finParamValues,AffVariableGroup=>{x},OutputStyle=>"OutSolutions")

o17 = {{{-1}, {1}}, {{-1.41421}, {1.41421}}}

o17 : List

i18 : class bPH1_0_0

o18 = Point

o18 : Type

i19 : class bPH2_0_0

o19 = List

o19 : Type

i20 : dir1 := temporaryFileName(); -- build a directory to store temporary data

i21 : makeDirectory dir1;

i22 : bPH5=bertiniParameterHomotopy( {"x^2-u1"}, {u1},{{1},{2}},AffVariableGroup=>{x},OutputStyle=>"OutNone",TopDirectory=>dir1)

i23 : B0=importSolutionsFile(dir1,NameSolutionsFile=>"ph_jade_0")

o23 = {{-1}, {1}}

o23 : List

i24 : B1=importSolutionsFile(dir1,NameSolutionsFile=>"ph_jade_1")

o24 = {{-1.41421}, {1.41421}}

o24 : List

Ways to use bertiniParameterHomotopy :

bertiniParameterHomotopy(List,List,List)

For the programmer

The object bertiniParameterHomotopy is a method function with options.