Hi Statalists,

I'm currently want to let stata calculate P1 for each id and here is a formula: P1 = A11 * D1 + ... + A18 * D4iii
(A11 is the first value of A1 which equals 0.345865; A12 is the second value of A1 which equals 0.326931 ; A13 is the third one and so on)

For example, if I want to get the P1 for first person, here is the calculation:
0.345865 (A11) * 1.566901 (D1 for ID == 1) + 0.326931 (A12) * 0.233873 (D2i for ID == 1) ..... + 0.321616 (A18) * 1.384699 (D4iii)

I find it laborious and I wonder if there is any more convenient way to calculate P1 for other IDs automatically?

If I also want to calculate P2 for first person after calculating P1, P2 = A21 * D1 + .... + A28 * D4iii, do I need to use some syntax like for loop?
id D1 D2i D2ii D3i D3ii D4i D4ii D4iii A1 A2
1 1.566901 0.233873 0.286958 0.556992 1.113236 1.567941 1.490475 1.384699 0.345865 -0.07561
2 -0.39339 -0.64672 0.07849 -0.88745 -0.2885 -0.57468 -0.70157 -0.59344 0.326931 0.470004
3 0.390256 1.464312 1.263042 0.840091 0.97695 -0.14107 -0.23965 -0.59344 0.320997 0.476968
4 -0.69505 -1.16996 -1.51789 -1.27133 -1.12446 -1.06964 -1.0088 -0.92313 0.367527 0.146237
5 -0.86872 0.118493 -0.1106 0.761692 -0.67723 0.217444 0.459544 0.725319 0.376543 0.223233
6 0.387949 -0.32069
7 0.373703 -0.36884
8 0.321616 -0.48557