The Calculator Site

The TI-82 The Ti-82 is a very good calculator and you can work very fast with it. When it comes to solve easy problems you solve them faster on this calculaton than whit the Ti89. I recommend this calculator to anybody who studying pre-university courses in mathematics. One shall be aware of that the Ti-82 will suit a lot of students even in the university. But if you need something extra, I really recommend the Ti-89. I list some of the things that I find especially useful about the Ti-82 below:

### The graph plotting and tracing

1. You can easily (and fast!) plot and trace functions like f=f(x).
2. It is easy to calculate intersection, minimum, maximum, derivative and integrals even though it's just numerious approximations.
3. Statistics can also be plotted and quite easily be approximated by graphs like Y(x)=A*e^(B*x) or Y(x)=A*x^2+B*x+C.

### The Basic programming language

1. I think that the programming facilities suffice for your common needs. If you want to create games or larger problem solvers you'll find out that it goes a bit slow. But you have a great amount of already implemented functions to create almost anything with.
2. If you are a programmer and want to be able to play games, you should not buy this one - buy the Ti89 (It supports fast assembler programming).

### The LIST-Editor

1. Use this is a great thing if you have many values and are going to make the same matematical operations on them all. Then you just open the editor: Stat/Edit.. and start to put your numbers in the list L1 for example. Then if you would like to calculate sinus of all your values you just go to the L2 column and write: L2=sin(L1) . After that you just press enter and all the values you put in the L1-list will be calculated all at once!
2. If you then go to the Stat/CALC menu you can select to show the statistics of one list. For example you can be shown the mean, max, sum and quantile values. All at the same time!

On this link you have a very useful program if you like to solve problems like Y(x)=A*x^2+B*x+C=0. The program works very well and has a lots of good features like: Find the roots, minimum, maximum, symerti line and it can plot the graph. You can even calculate problems with imaginary-roots! (You can actually work very fast using this tool).
You can also downoad the program file if you have a link cable here:

### Functions and tools that I like the most

1. The >FRAC funcion: Use this if you've got an answer like: 1.857142857 Now you just have to select the >FRAC function in the math menu to get the number above to be displayed like 13/7 . If you hade the number 0.3333333 you would get the result 1/3 .
2. The SOLVE( function: This is a tool on the math menu to solve functions numerically (almost the same as the intersection function). If you would like to solve x^3-2*x^(1/3)+5=0 you just type: solve(x^3-2*x^(1/3)+5,x,0) to get the solution -1.9576 .
3. The 2nd ENTRY button (the 2nd Enter) will recall what you've been writing earlier. So you can fast and easily bring back things you've calculated and modify them to calculate them again.

The TI-89 The Ti-89 is probebly the best pocket-calculator that exists. But I havn't tried the hp49G calculator really well yet. But it seemed a lettle bit too slow when I tried to do some simple calculations like 13*14/5. The Ti-89 makes those calculations very fast. The fact that you get used to the calculator which you've used for a long time makes it hard to really get a good opinion about the HP calculators. But some differences I want you to note:

1. The desigd: HP49G has a very good design with its soft keys an blue color. The Ti-89 has a good design too but the HP49G wins that battle with no problem. Click here for a large picture of the HP49G
2. The feeling when using it: The Ti-89 is fast and good but the HP49G is sadly very slow when you're calculating the easiest of calculations. It's like sitting by an very old PC still running win98! That's why I really recommend that you try the HP before you buy it.
3. The Price: The HP49G is more expensive, maybe costs about 170 % of the price of the Ti-89.
I think you understand by now that if you are going to buy a new calculator I really recommend the Ti-82 if you think you wont need the extra features in the Ti-89. If you are an university student who are interested in matematics I really recommend the Ti-89. It's actually the best pocket calculator that exists, in my opinion. The features that I find especially useful about the Ti-89 is listed below:

### Things that don't exists on the ti-82

1. Exact calculations: the result comes out in axact form. If you type (2x+(2x+8)^2)/4 the result will show (2x^2+17x+32)/2 or if you type 3/4+3/5 the result will be 27/20 or 1.35 (depends on your settings).
2. Fast buttons: You can program the buttons 1-9 with your own programs. So when you press STAR-KEY + 1 the program under button 1 will start. This is fast and easy!
3. Program your own custom menu: there exists an extra menu in the calculator that you can design yourself.
4. Powerful functions: You can integrate, diffrentiate, expand and factor an expression. You can also calculate limits, sums and products of series. You can do taylor expansions and also plot and solve differential equations numerically either with Runge-Kutta or Eulers methods.
5. You can create matixes and do all the common operations on them.
6. You can program in assembler code which gives huge speed to the calculations or the games. You can also program in the much easier basic language.

I have programmed a program that solves the equation system problem Ax=b. The program is programmed in Ti-basic and I admit that the code could be better. But the thing is that it woks and works well. It uses actually the already built in solve() function but translates the matrixes to a form that the function can understand. The function solve() usually uses the Gauss-Elimination method and can handle equation systems up to maybe 10 unknown variables not taking too much time. The program works fast with as lage as an 6*6 big A-matrix but can calculate bigger systems too - but the working time will increase rapidly for systems having A-matrix bigger then 10*10. You should learn how to use it because when it comes to solve equation systems you save lots of time using the matrix notations. Please believe me!

### An easy example

If you have the following equation system:  