let p be FinSequence of REAL ; :: thesis: for M being Matrix of 3,REAL
for a, b, c, d, e, f, g, h, i, p1, p2, p3 being Element of REAL st M = <*<*a,b,c*>,<*d,e,f*>,<*g,h,i*>*> & p = <*p1,p2,p3*> holds
M * p = <*(((a * p1) + (b * p2)) + (c * p3)),(((d * p1) + (e * p2)) + (f * p3)),(((g * p1) + (h * p2)) + (i * p3))*>

let M be Matrix of 3,REAL; :: thesis: for a, b, c, d, e, f, g, h, i, p1, p2, p3 being Element of REAL st M = <*<*a,b,c*>,<*d,e,f*>,<*g,h,i*>*> & p = <*p1,p2,p3*> holds
M * p = <*(((a * p1) + (b * p2)) + (c * p3)),(((d * p1) + (e * p2)) + (f * p3)),(((g * p1) + (h * p2)) + (i * p3))*>

let a, b, c, d, e, f, g, h, i, p1, p2, p3 be Element of REAL ; :: thesis: ( M = <*<*a,b,c*>,<*d,e,f*>,<*g,h,i*>*> & p = <*p1,p2,p3*> implies M * p = <*(((a * p1) + (b * p2)) + (c * p3)),(((d * p1) + (e * p2)) + (f * p3)),(((g * p1) + (h * p2)) + (i * p3))*> )
assume that
A1: M = <*<*a,b,c*>,<*d,e,f*>,<*g,h,i*>*> and
A2: p = <*p1,p2,p3*> ; :: thesis: M * p = <*(((a * p1) + (b * p2)) + (c * p3)),(((d * p1) + (e * p2)) + (f * p3)),(((g * p1) + (h * p2)) + (i * p3))*>
A3: ( p . 1 = p1 & p . 2 = p2 & p . 3 = p3 ) by A2, FINSEQ_1:45;
p = |[p1,p2,p3]| by A2;
then reconsider ru = p as Element of REAL 3 by EUCLID:22;
A4: MXR2MXF (ColVec2Mx p) = <*ru*> @ by ANPROJ_8:72;
reconsider a = a, b = b, c = c, d = d, e = e, f = f, g = g, h = h, i = i as Element of F_Real ;
reconsider fu1 = ru . 1, fu2 = ru . 2, fu3 = ru . 3 as Element of F_Real by XREAL_0:def 1;
A5: <*ru*> @ = <*<*fu1*>,<*fu2*>,<*fu3*>*> by EUCLID_8:50, ANPROJ_8:77;
A6: len ru = 3 by EUCLID_8:50;
A7: len <*ru*> = 1 by FINSEQ_1:39;
rng <*ru*> = {ru} by FINSEQ_1:39;
then ru in rng <*ru*> by TARSKI:def 1;
then A8: width <*ru*> = 3 by A6, A7, MATRIX_0:def 3;
then A9: width (<*ru*> @) = len <*ru*> by MATRIX_0:29
.= 1 by FINSEQ_1:39 ;
A10: len (<*ru*> @) = 3 by MATRIX_0:def 6, A8;
then A11: <*ru*> @ is Matrix of 3,1,F_Real by A9, MATRIX_0:20;
reconsider M2 = <*ru*> @ as Matrix of 3,1,F_Real by A10, A9, MATRIX_0:20;
A12: M * (ColVec2Mx p) = M * (<*ru*> @) by A4, MATRIXR1:def 1
.= MXF2MXR ((MXR2MXF M) * (MXR2MXF (<*ru*> @))) by MATRIXR1:def 6 ;
A13: MXR2MXF (<*ru*> @) is Matrix of 3,1,F_Real by MATRIXR1:def 1, A11;
A14: MXR2MXF (<*ru*> @) = <*<*fu1*>,<*fu2*>,<*fu3*>*> by A5, MATRIXR1:def 1;
A15: (MXR2MXF M) * (MXR2MXF (<*ru*> @)) = <*<*(((a * fu1) + (b * fu2)) + (c * fu3))*>,<*(((d * fu1) + (e * fu2)) + (f * fu3))*>,<*(((g * fu1) + (h * fu2)) + (i * fu3))*>*> by A13, A1, MATRIXR1:def 1, A14, ANPROJ_9:7;
reconsider q = <*(((a * fu1) + (b * fu2)) + (c * fu3)),(((d * fu1) + (e * fu2)) + (f * fu3)),(((g * fu1) + (h * fu2)) + (i * fu3))*> as FinSequence of REAL ;
A16: ( q . 1 = ((a * fu1) + (b * fu2)) + (c * fu3) & q . 2 = ((d * fu1) + (e * fu2)) + (f * fu3) & q . 3 = ((g * fu1) + (h * fu2)) + (i * fu3) ) by FINSEQ_1:45;
q = |[(((a * fu1) + (b * fu2)) + (c * fu3)),(((d * fu1) + (e * fu2)) + (f * fu3)),(((g * fu1) + (h * fu2)) + (i * fu3))]| ;
then reconsider rq = q as Element of REAL 3 by EUCLID:22;
reconsider qf = q as FinSequence of F_Real ;
A17: len q = 3 by FINSEQ_1:45;
A18: ColVec2Mx rq = MXR2MXF (ColVec2Mx rq) by MATRIXR1:def 1
.= <*qf*> @ by ANPROJ_8:72 ;
then A19: ColVec2Mx rq = F2M q by A17, ANPROJ_8:88
.= <*<*(((a * fu1) + (b * fu2)) + (c * fu3))*>,<*(((d * fu1) + (e * fu2)) + (f * fu3))*>,<*(((g * fu1) + (h * fu2)) + (i * fu3))*>*> by A16, A17, ANPROJ_8:def 1
.= M * (ColVec2Mx p) by A15, A12, MATRIXR1:def 2 ;
M * p = Col ((ColVec2Mx rq),1) by A19, MATRIXR1:def 11
.= <*(((a * fu1) + (b * fu2)) + (c * fu3)),(((d * fu1) + (e * fu2)) + (f * fu3)),(((g * fu1) + (h * fu2)) + (i * fu3))*> by A18, ANPROJ_8:93 ;
hence M * p = <*(((a * p1) + (b * p2)) + (c * p3)),(((d * p1) + (e * p2)) + (f * p3)),(((g * p1) + (h * p2)) + (i * p3))*> by A3; :: thesis: verum