В чем ошибка (js) ? N=NaN

A = [ 
  [1, 20], 
  [4, 10], 
  [9, 3] 
]; 
x = [7, 1, 6]; 
y = [0.3, 0.4]; 
 
var ay = []; 
 
for (i = 0; i < n; i++) 
  for (j = 0; j < m; j++) { 
    ay[i] += A[i] * y[j]; 
  } 
 
sk = 0; 
 
for (i = 0; i <= n; i++) { 
  v[i] += ay[i] * x[i]; 
  sk += v[i]; 
} 
 
n1 = sk * m * n; 
console.log('N=', n1);