# subPoint -- This function evaluates a polynomial or matrix at a point.

## Synopsis

• Usage:
subPoint(f,v,p)
• Inputs:
• f, , A polynomial or a matrix.
• v, a list, List of variables that we will be evaluated at the point.
• p, , A point or a list of coordinates or a matrix.
• Optional inputs:
• M2Precision (missing documentation) => ..., default value 53,
• SpecifyVariables (missing documentation) => ..., default value false,
• SubIntoCC (missing documentation) => ..., default value false,

## Description

Evaluate f at a point.

 i1 : R=CC[x,y,z] o1 = R o1 : PolynomialRing i2 : f=z*x+y o2 = x*z + y o2 : R i3 : subPoint(f,{x,y},{.1,.2}) o3 = .1z + .2 o3 : R i4 : subPoint(f,{x,y,z},{.1,.2,.3},SpecifyVariables=>{y}) o4 = x*z + .2 o4 : R
 i5 : R=CC_200[x,y,z] o5 = R o5 : PolynomialRing i6 : f=z*x+y o6 = x*z + y o6 : R i7 : subPoint(f,{x,y,z},{.1,.2,.3},SubIntoCC=>true) o7 = .23 o7 : CC (of precision 53) i8 : subPoint(f,{x,y,z},{.1234567890123456789012345678901234567890p200, 0,1},SubIntoCC=>true,M2Precision=>200) o8 = .123456789012345678901234567890123456789 o8 : CC (of precision 200)

## Caveat

When SubIntoCC is set to true then unset variables will be set to zero or unexpected values.

## Ways to use subPoint :

• "subPoint(Thing,List,Thing)"

## For the programmer

The object subPoint is .