STEMCD

This page is devoted to presenting, in a step by step fashion, the keystrokes and the screen images for doing a using the STEMCD program on a TI-83 (TI-83 Plus, or TI-84 Plus) calculator. The STEMCD program is a revision of the STEM10 program where the added feature is to allow the user to specify the location of a "cut point" in the data being processed. The "cut point" is the location in the numbers that separates the "stem" from the "leaf" values.

We will generate a list of data on the calculator, using GNRND4 with Key 1=3542173204 and Key 2=8437592. That list will be the same numbers that appear in the following table: Thus, our problem will be to generate a stem-and-left diagram for the data in the list above.

Figure 1 Here we have started the GNRND4 program and given it the two specified keys. We finish by using the key.

Figure 2 The program responds with Figure 2. We continue by using the key.

Figure 3 Figure 3 gives some more information. We continue by using the key.

Figure 4 The program does its work generating the values, which are stored in L₁. We conclude by pressing the key. The calculator responds with Done. We can see that the first two values in the list are identical to those in the table above. We could have used the key to scroll across the rest of the list but this is a slow and painful process.
Instead we will use the key to open the STAT menu and the key to open the stat editor. The result is shown in Figure 5.

Figure 5 Here we can see the first seven (7) values in the list. There are exactly the values given in the table above. If we wnted to we could use the key to scroll down the list to verify the rest of the values.
Now that we have the values in the calculator, we can use the STEMCD program to create a stem and leaf diagram.

Figure 6 We use the key to open the program menu. Then we move the highlight down to the STEMCD name. At that point we press to cause the calculator to paste the desired command onto the main screen.

Figure 7 Once the desired command, in this case prgmSTEMCD, has been pasted onto the main screen, we press to start the program.

Figure 8 The program introduces itself and then asks for the location of the data. We indicate that it is in L₁ by pressing . Then, to continue with the program we press .

Figure 9 The STEMCD program reviews the data and then gives us three values, the minimum value in the list, the maximum value in the list, and the number of items in the list.
These are useful in helping us determine where we want to "cut" the numbers between the "stem" and the "leaf". For the values in our table (list) it is pretty clear that we want to have the "stem" be the values from the tenths place to the left. Thus, our lowest "stem" should be 37.3 and the highest should be 37.7. In fact, at this point we know that we will have 5 stems and that our diagram, without the leaf values, will be
37.3:
37.4:
37.5:
37.6:
37.7:
The progam is waiting for our signal to continue, so we press .

Figure 10 The program now asks us for the location of the "cut point". It does this by giving us a pseudo-number in the form of ABCDE.FGHIJ and asking us for the two character sequence that marks either side of the "cut point", CP.

Figure 11 For the data that we are using we had determined that we want the "cut point" to be between the tenths and hundredth places. In the pseudo-number ABCDE.FGHIJ that means we want the "cut-point" between the F and the G. Therefore we respond with FG via the sequence . Then press to continue the program.

Figure 12 STEMCD clears the screen and then starts to display the stem and leaf diagram, one line at a time. Figure 12 shows the first line, 373:8, which is what we expected, although the STEMCD does not display the decimal point. Press to continue.

Figure 13 Now we have the second line. Press to continue.

Figure 14 Figure 14 adds the third line to the display. Press to continue.

Figure 15 Figure 15 adds the fourth line to the display. In this case the line is too long to fit on the screen so STEMCD wraps it around onto the next line. Press to continue.

Figure 16 Now we have the fifth line. Press to continue.

Figure 17 The program concludes by printing COMPLETED.

Let us consider a second example. As usual, we will generate a list of data on the calculator, this time using GNRND4 with Key 1=473282704 and Key 2=6878732. That list will be the same numbers that appear in the following table: Thus, our problem will be to generate a stem-and-left diagram for the data in the list above.

Figure 18 We start by generating the numbers given in the table above on the calculator, running GNRND4 and entering the specified values for the two keys. We then use to continue the program.

Figure 19 Figure 19 shows the conclusion of the program, having skipped over the two intermediate output screens. We can verify that we have exactly the same values on the calculator that we had in the given table.

Figure 20 We use the key t go to the list of programs, move down the list to highlight STEMCD, use to select that program and paste the prgmSTEMCD line on the main screen. Then press to run the program.

Figure 21 The program asks us for the location of the data. We use to tell it that the data is in L₁. Then press to continue.

Figure 22 The program inspects the data and gives us the low and high values along with the number of values. We see that a reasonable stem and leaf diagram would have the stems:
785:
786:
787:
788:
Thus, we want the cut point between the hundreds palce and the tens place. Press to continue.

Figure 23 The program uses the pseudo-number ABCDE.FGHIJ to request the location of the cut point. We respond by using to indicate our choice of CD. Press to continue.

Figure 24 Figure 24 shows the completed run of the program, after we have used the key repeatedly to step through each line of output.

Figure 1	Here we have started the GNRND4 program and given it the two specified keys. We finish by using the key.
Figure 2	The program responds with Figure 2. We continue by using the key.
Figure 3	Figure 3 gives some more information. We continue by using the key.
Figure 4	The program does its work generating the values, which are stored in L₁. We conclude by pressing the key. The calculator responds with Done. We can see that the first two values in the list are identical to those in the table above. We could have used the key to scroll across the rest of the list but this is a slow and painful process. Instead we will use the key to open the STAT menu and the key to open the stat editor. The result is shown in Figure 5.
Figure 5	Here we can see the first seven (7) values in the list. There are exactly the values given in the table above. If we wnted to we could use the key to scroll down the list to verify the rest of the values. Now that we have the values in the calculator, we can use the STEMCD program to create a stem and leaf diagram.
Figure 6	We use the key to open the program menu. Then we move the highlight down to the STEMCD name. At that point we press to cause the calculator to paste the desired command onto the main screen.
Figure 7	Once the desired command, in this case prgmSTEMCD, has been pasted onto the main screen, we press to start the program.
Figure 8	The program introduces itself and then asks for the location of the data. We indicate that it is in L₁ by pressing . Then, to continue with the program we press .
Figure 9	The STEMCD program reviews the data and then gives us three values, the minimum value in the list, the maximum value in the list, and the number of items in the list. These are useful in helping us determine where we want to "cut" the numbers between the "stem" and the "leaf". For the values in our table (list) it is pretty clear that we want to have the "stem" be the values from the tenths place to the left. Thus, our lowest "stem" should be 37.3 and the highest should be 37.7. In fact, at this point we know that we will have 5 stems and that our diagram, without the leaf values, will be 37.3: 37.4: 37.5: 37.6: 37.7: The progam is waiting for our signal to continue, so we press .
Figure 10	The program now asks us for the location of the "cut point". It does this by giving us a pseudo-number in the form of ABCDE.FGHIJ and asking us for the two character sequence that marks either side of the "cut point", CP.
Figure 11	For the data that we are using we had determined that we want the "cut point" to be between the tenths and hundredth places. In the pseudo-number ABCDE.FGHIJ that means we want the "cut-point" between the F and the G. Therefore we respond with FG via the sequence . Then press to continue the program.
Figure 12	STEMCD clears the screen and then starts to display the stem and leaf diagram, one line at a time. Figure 12 shows the first line, 373:8, which is what we expected, although the STEMCD does not display the decimal point. Press to continue.
Figure 13	Now we have the second line. Press to continue.
Figure 14	Figure 14 adds the third line to the display. Press to continue.
Figure 15	Figure 15 adds the fourth line to the display. In this case the line is too long to fit on the screen so STEMCD wraps it around onto the next line. Press to continue.
Figure 16	Now we have the fifth line. Press to continue.
Figure 17	The program concludes by printing COMPLETED.

Figure 18	We start by generating the numbers given in the table above on the calculator, running GNRND4 and entering the specified values for the two keys. We then use to continue the program.
Figure 19	Figure 19 shows the conclusion of the program, having skipped over the two intermediate output screens. We can verify that we have exactly the same values on the calculator that we had in the given table.
Figure 20	We use the key t go to the list of programs, move down the list to highlight STEMCD, use to select that program and paste the prgmSTEMCD line on the main screen. Then press to run the program.
Figure 21	The program asks us for the location of the data. We use to tell it that the data is in L₁. Then press to continue.
Figure 22	The program inspects the data and gives us the low and high values along with the number of values. We see that a reasonable stem and leaf diagram would have the stems: 785: 786: 787: 788: Thus, we want the cut point between the hundreds palce and the tens place. Press to continue.
Figure 23	The program uses the pseudo-number ABCDE.FGHIJ to request the location of the cut point. We respond by using to indicate our choice of CD. Press to continue.
Figure 24	Figure 24 shows the completed run of the program, after we have used the key repeatedly to step through each line of output.