Border Curves

Pick off some points along the US/Mexico border. You do not need to hold the "apple" button down constantly; just click on some points along the border.


  points={{0.105085, 0.311864}, {0.125424, 0.308475}, 
  {0.142373, 0.305085}, {0.147458, 0.301695}, 
  {0.154237, 0.29661}, {0.166102, 0.289831}, 
  {0.177966, 0.283051}, {0.189831, 0.276271}, 
  {0.201695, 0.269492}, {0.210169, 0.264407}, 
  {0.222034, 0.262712}, {0.237288, 0.259322}, 
  {0.250847, 0.255932}, {0.264407, 0.254237}, 
  {0.267797, 0.259322}, {0.271186, 0.264407}, 
  {0.281356, 0.261017}, {0.291525, 0.261017}, 
  {0.30339, 0.259322}, {0.310169, 0.250847}, 
  {0.316949, 0.240678}, {0.327119, 0.233898}, 
  {0.332203, 0.222034}, {0.337288, 0.208475}, 
  {0.345763, 0.2}, {0.354237, 0.194915}, 
  {0.362712, 0.189831}, {0.366102, 0.2}, 
  {0.376271, 0.208475}, {0.386441, 0.208475}, 
  {0.39661, 0.205085}, {0.40339, 0.19661}, 
  {0.410169, 0.186441}, {0.416949, 0.172881}, 
  {0.425424, 0.162712}, {0.428814, 0.150847}, 
  {0.432203, 0.140678}, {0.438983, 0.130508}, 
  {0.450847, 0.125424}, {0.462712, 0.122034}, 
  {0.471186, 0.118644}};


  ListPlot[points, AspectRatio->Automatic];


  usmexborder=SplineFit[points,Cubic]


  ParametricPlot[usmexborder[x],{x,0,14},PlotRange->All,Compiled->False];

You can evaluate the function usmexborder at any point along the border. Remember that the spline curve is a parametric curve; you you enter a parameter within the range of the parametrization and the output is the (x,y) pair at that parameter.


  usmexborder[0]
  usmexborder[14]

The following command gives the type of spline (Cubic), the points used, and the coefficients of the polynomials that make up the spline (if you really want to know the function). See the next example.


  InputForm[usmexborder]

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