Least Square solution

a1*x+b1*y=k1
a2*x+b2*y=k2
a3*x+b3*y=k3

   |a1 b1|     |k1|     |x|
B= |a2 b2|  C= |k2|  N= |y|
   |a3 b3|     |k3|

Bt is transpose  of B

Example

    | 3   4   |      | 23 |
B = | 2.2 7.2 |  C = | 20 |
    | 9.2 6.1 |      | 44 |

z=(Bt*B)^(-1)*Bt*c

  | 3.65452 |      | x |
N=| 1.88069 |   =  | y |

test of solution

3   * x + 4   * y  = 18.4863
2.2 * x + 7.2 * y  = 21.5809
9.2 * x + 6.1 * y  = 45.0938

See http://mathworld.wolfram.com/Moore-PenroseMatrixInverse.html

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System is underdefined

Example
  w x y z
| 2 3 4 5 |
| 5 1 6 4 | -> B
| 8 9 1 2 | 

| 40 |
| 41 | -> C
| 37 |

Bt*(B*Bt)^(-1) *c -> N


    | 0.978043 |   | w |
N = | 2.02321  | = | x |
    | 3.03027  |   | y |
    | 3.96424  |   | z |

2*w +  3*x +  4*y + 5*z = 40
5*w +  1*x +  6*y + 4*z = 41
8*w +  9*x +  1*y + 2*z = 37

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