Equation Icon   ( )( ) y21(t) = 1 - ^k .^n3 Y3(t + ^k .p2 - L) - Y3(t + ^k .p1) , (1) ( )( ) y31(t) = 1 + ^k .^n2 Y2(t + ^k .p3 - L) - Y2(t + ^k .p1) , (2)