\left[ {\begin{array}{*{20}c}
 1 & {T_1 } \\
 1 & {T_2 } \\
 1 & {T_3 } \\
\end{array}} \right]\left[ {\begin{array}{*{20}c}
 b \\
 a \\
\end{array}} \right] \approx \left[ {\begin{array}{*{20}c}
 {p_1 } \\
 {p_2 } \\
 {p_3 } \\
\end{array}} \right]