Defining a symbol in a TI 84 pluss

Hi. Basically iam trying to multiply 2 matrices together. The first matrix (A) is purely constants, but the second matrix (B) contains terms like:

cos(314.15.X + (2pi/3))

How can i define "X" so that when i multiply the two matrices "A" and "B" the answer is expressed in terms of cos(314.15.X +.......)
and not simply solved for whatever the saved value of X happens to be.

Many thanks

John

Sorry, that's the way the 83 and 84 store values into variables (and lists, and matrices). The closest thing you could do to imitate this is to use imaginary numbers, assuming everything will be in the same format...however it would only work if you had all of your statements in matrix [B] be like cos(AX+Bpi), where A is the real value in the imaginary number, and B would be the imaginary part. In other words, you'd need to find some other way to tell it if you wanted it to use sine, cosine, tangent, and so on.

If all of your statements are some deviation of cos(AX+Bpi), then using imaginary numbers would work perfectly for you. But if you also need sine, and cosine, and all the others, then you may need to use a third matrix to tell the program which cells in matrix [B] are sine, which and cosine, and so on.

I'd help you out, but I'm fairly busy right now. If I get the time I'll try to make something to help you out. But either way, tell me how the program ends up for you.

Thankyou very much for the reply. I'm trying to work it out like that. Do you know if the new TI 89 is capable of doing this without having to imitate the problem?

From the limited times I've had the pleasure of using the 89, I believe it does something similar, but not entirely the same. I believe it will simplify the variable into a value, but it will leave everything inside the cosine as it is, even separating the integer from the fractioned pi. But I never tested that out, so I'm not sure. There is a chance that it will leave the variable as is, but no guarantees.
Of all the TI calculators though, that one and the 92 are the most likely to do that. I'm not sure if I'd suggest to you to use the newer calculators though, as with limited tools, comes greater challenges that only great programmers could overcome with similar if not the same speed, but much greater efficiency.

Let me put it to you this way. Ever notice that the programmers of big budget console and PC games almost always have extremely unoptimized codes? Do you think that a programmer for the 83 + would survive in the programming community if he was trying to sell a game he made, but was really slow because he never optimized it? In a way you could say that the programmers for these big games are cheating, with their quad core processors, huge supplies of RAM, and other fancy computer parts, when we have a little z80 processor used in the original GameBoy, a 63x95 black and white screen, and 4 AAA batteries, and we still produce much more efficiently programmed games that are ignored by the general population.

My point is, if you're into this for the programming, I'd suggest you stick with the 84 + SE, if not downgrade to the 83 or 83 +. If your into this for this one problem, then you may as well use your 89.