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 [b,a] = butter(4,0.001,'high')

b =

  Columns 1 through 4 

   0.99590372213842  -3.98361488855370   5.97542233283055  -3.98361488855370

  Column 5 

   0.99590372213842


a =

  Columns 1 through 4 

   1.00000000000000  -3.99179062441447   5.97540555338674  -3.97543915264442

  Column 5 

   0.99182422376917

 [b,a] = butter(4,0.00125,'high')

b =

  Columns 1 through 4 

   0.99488227577504  -3.97952910310017   5.96929365465026  -3.97952910310017

  Column 5 

   0.99488227577504


a =

  Columns 1 through 4 

   1.00000000000000  -3.98973828167001   5.96926746366732  -3.96931992441204

  Column 5 

   0.98979074265133

 [b,a] = butter(4,0.0015,'high')

b =

  Columns 1 through 4 

   0.99386187613446  -3.97544750453785   5.96317125680678  -3.97544750453785

  Column 5 

   0.99386187613446


a =

  Columns 1 through 4 

   1.00000000000000  -3.98768593969348   5.96313358048725  -3.96320906913718

  Column 5 

   0.98776142883352

 [b,a] = butter(4,0.00175,'high')

b =

  Columns 1 through 4 

   0.99284252196093  -3.97137008784372   5.95705513176558  -3.97137008784372

  Column 5 

   0.99284252196093


a =

  Columns 1 through 4 

   1.00000000000000  -3.98563359863846   5.95700390272723  -3.95710657659545

  Column 5 

   0.98573627341374

 [b,a] = butter(4,0.002,'high')

b =

  Columns 1 through 4 

   0.99182421200053  -3.96729684800213   5.95094527200320  -3.96729684800213

  Column 5 

   0.99182421200053


a =

  Columns 1 through 4 

   1.00000000000000  -3.98358125865852   5.95087842926670  -3.95101243657283

  Column 5 

   0.98371526751048

 [b,a] = butter(4,0.003,'high')

b =

  Columns 1 through 4 

   0.98776138927683  -3.95104555710730   5.92656833566096  -3.95104555710730

  Column 5 

   0.98776138927683


a =

  Columns 1 through 4 

   1.00000000000000  -3.97537191256092   5.92641855596542  -3.92671919775679

  Column 5 

   0.97567256214609

 [b,a] = butter(4,0.004,'high')

b =

  Columns 1 through 4 

   0.98371517412976  -3.93486069651902   5.90229104477854  -3.93486069651902

  Column 5 

   0.98371517412976


a =

  Columns 1 through 4 

   1.00000000000000  -3.96716259594885   5.90202586149088  -3.90255878482324

  Column 5 

   0.96769554381314

 [b,a] = butter(4,0.005,'high')

b =

  Columns 1 through 4 

   0.97968548719040  -3.91874194876162   5.87811292314243  -3.91874194876162

  Column 5 

   0.97968548719040


a =

  Columns 1 through 4 

   1.00000000000000  -3.95895331864708   5.87770027353615  -3.87853054905174

  Column 5 

   0.95978365381150

 