Arduino parallel 8 bit DAC sine wave generator sketch

#include <TimerOne.h>

/* Arduino parallel 8 bit DAC sine wave output generator using Timer1*/

/* NOTE: I used MATLAB or Octave to generate the tabulated data below. Here's the code:
clear
clc

f=1000;
fs=20000;
M=floor(fs/f);

disp(M);

disp(['{(byte)(127.0+127.0*sin(2.0*3.1416*' num2str(f) '*' num2str(0) '/' num2str(fs) ')),']);
for n=1:(M-2)
    disp(['(byte)(127.0+127.0*sin(2.0*3.1416*' num2str(f) '*' num2str(n) '/' num2str(fs) ')),']);
end
disp(['(byte)(127.0+127.0*sin(2.0*3.1416*' num2str(f) '*' num2str(M-1) '/' num2str(fs) '))};']);
*/

byte table[20]={(byte)(127.0+127.0*sin(2.0*3.1416*1000*0/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*1/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*2/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*3/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*4/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*5/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*6/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*7/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*8/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*9/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*10/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*11/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*12/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*13/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*14/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*15/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*16/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*17/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*18/20000)),
(byte)(127.0+127.0*sin(2.0*3.1416*1000*19/20000))};

byte n=0;

void setup()
{
  // Initialize the digital pin as an output.
  pinMode(0, OUTPUT);
  pinMode(1, OUTPUT);
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);

  Timer1.initialize(50);
  Timer1.attachInterrupt( timerIsr ); // attach the service routine here
}

void loop()
{
  // Main code loop
  // Nothing here
}

/// --------------------------
/// Custom ISR Timer Routine
/// --------------------------
void timerIsr()
{
    byte temp;
    temp=table[n];
    PORTD=temp;
    digitalWrite(8,digitalRead(8)^1);
    n++;
    n=(n>19)?0:n; //MODIFY TO MATCH M-1
}