# Difference between revisions of "ApCoCoA-1:Num.RatPoints"

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## Latest revision as of 13:48, 29 October 2020

This article is about a function from ApCoCoA-1. |

## Num.RatPoints

Computes the zero set of an exact zero dimensional border basis. The zeros are computed approximately using the eigenvalues of the transposed multiplication matrices.

### Syntax

Num.RatPoints(BB:LIST, OrderIdeal:LIST)):LIST of MAT

### Description

*Please note:* The function(s) explained on this page is/are using the *ApCoCoAServer*. You will have to start the ApCoCoAServer in order to use it/them.

This command computes a set of points, which are the zeros of an exact border basis. This border basis is close to the approximate border basis `AppBB`. The set of (complex) points is represented as two matrices. The `j`-th column of the first matrix gives the real part of a point and the `j`-th column of the second matrix gives the imaginary part. For computation the function is using the Num.EigenValues command.

@param

*AppBB*An approximate border basis.@param

*OrderIdeal*The associated order ideal@return A set of points in matrix form described above.

#### Example

Use P::=QQ[x,y,z]; Points := Mat([[2/3,0,0],[0,10,0],[0,0,1/3]]); R:=Num.ABM(Points, 0); Dec(Num.RatPoints(R[1],R[2]),2); -- CoCoAServer: computing Cpu Time = 0 ------------------------------- -- CoCoAServer: computing Cpu Time = 0.016 ------------------------------- [Mat([ ["0.66", "0.00", "0"], ["0", "0", "10"], ["0", "0.33", "0"] ]), Mat([ ["0", "0", "0"], ["0", "0", "0"], ["0", "0", "0"] ])] -------------------------------

### See also