Question about Texas Instruments TI-89 Calculator

# I am trying to graph an equation, but the screen says undefined variable. On the y= screen I have 9 plots , with plot 1 listed as x:main\x y:main\y. The equation I entered was y1(x)=x^2-4 Please tell me how to fix this! Thank you!

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• Karma Mygrant Mar 11, 2011

Are you trying to graph just the function or a scatter plot?

• vbourne Mar 11, 2011

just the function.
I got it working (somehow)... not sure what was wrong.
I went to F5 Then Reset Styles. and this worked.

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• Expert

I''m glad you got this to work. For anyone else with this problem, in the y = page you can go to f5 and reset the settings, or you can highlight the plot 1 line and press [clear] this will not clear any other settings you may have inputted.

Posted on Mar 11, 2011

Hi,
a 6ya Technician can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repair professionals here in the US.
Goodluck!

Posted on Jan 02, 2017

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## Related Questions:

### ERR: STAT PLOT

ERR: STAT PLOT meaning tha you are trying to display a graph when there is a StatPlot On that uses an undefined list

Feb 01, 2013 | Texas Instruments TI-82 Calculator

### I cannot figure out how to do a Quadreg

Your question is a very interesting one and I believe people will benefit from a complete solution to it. So I will provide a solution for a quadratic regression.
The points I will represent are those on a parabola
L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}
As you can see, I am cheating (no experimental points will fit a perfect parabola) but this will have no incidence on what I am going to show you.

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.

2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]

to open the list editing screen. Enter the elements of the two lists

After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below

Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to Xlist
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)

DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitly on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen

Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line

After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
Type in the value and press [ENTER] et voilà.

If as I have suggested above, you copied the regression equation to Y1 variable, you can calculate Y-values for any X in the graph domain.

In Main calculator screen type the numerical value of X, say 4.777756, and store it in X-variable

4.777756 [STO>] [X,T,theta,n] [ENTER]

Press [VARS][>][Y-VARS][1:Function...][1:Y1] [ENTER]

The calculator computes the value of Y1 for the entered value of X.
You can also generate a whole table, but you will have less control over the points where Y1 will be calculated.

Dec 08, 2010 | Texas Instruments TI-84 Plus Silver...

### In my Y= menu, any equation that I enter isn't graphed on my graph. At the top, by Plot 1 Plot 2 Plot 3, it says "X=" before them. Also when i do enter an equation, it says Error: invalid dimensions.

You must deactivate the Statistical plots.
Press [STAT].
In list that is displayed delect [4:PlotsOff] and press [ENTER]
Go to [Y=] editor to enter functions or press [GRAPH] if functions already entered.

Oct 20, 2010 | Texas Instruments TI-84 Plus Calculator

### When I enter the Regression Equation into the "y=" calculated from the Statistics that I input, it inputs half the equation into the power. Like X^(n 3) instead of X^(n) 3 which is what it is meant to be.

The regression equation can be copied automatically in a Yx variable. You need not enter it manually(?).
Example: Suppose you are performing a quadratic regression on data stored in L1 and L2.
1. From the [Stat][

Oct 12, 2010 | Texas Instruments TI-84 Plus Silver...

### How do i find the line of best fit on my TI-84 plus addition?

Here is a complete solution that shows you how to find the equation for the best curve fitting, how to draw that equation on the same screen as the scatter plot and also how to do interpolation or the best fit curve. The post may seem long for an impatient reader but it leaves no stone unturned. Please DO READ it till the end.

The data points used are for a parabola (QuadReg) but you can easily adapt it

The points I will represent are those on a parabola (squares of all integer numbers from 0 to 10). Substitute your own values in L1 and L2

L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.

2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]

to open the list editing screen. Enter the elements of the two lists

After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below

Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to Xlist
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)

DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitly on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen

Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line

After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
Type in the value and press [ENTER] et voil

Sep 01, 2010 | Texas Instruments TI-84 Plus Silver...

### How do i find and use the regression capabilties of my calculator?

Your question is a very interesting one and I believe people will benefit from a complete solution to it. So I will provide a solution but I will apply it to a quadratic regression.
The points I will represent are those on a parabola
L1= {0,1,2,3,4,5,6,7,8,9,10}
L2={0,1,4,9,16,25,36,49,64,81,100}
As you can see, I am cheating (no experimental points will fit a perfect parabola) but this will have no incidence on what I am going to show you.

1. PREPARE THE GRAPH FORMAT (you will see why latter)
With the calculator turned On, press [2nd][ZOOM] to access the (FORMAT) screen. Notice that RectGC is highlighted. It means that the coordinates are rectangular. IF the POLARGC had been highlighted and you had used the TRACE function the values of the coordinates of the points being traced would be in the form (R, theta), in other words polar coordinates.

2. ENTER THE DATA

Press STAT, then under the EDIT menu press [1:Edit]

to open the list editing screen. Enter the elements of the two lists

After you enter the data in L1 and L1, Press [2nd][Y=] to open the (STAT PLOT)

3. CONFIGURE THE STAT PLOT TYPE

Initially the Plot1 may be OFF. Make sure at the beginning that all Stat Plots are OFF. If necessary press [4:PlotsOff] execute the command in Main calculator screen and press [2nd][Y=1] to get back at the stat plot screen configuration below

Press 1:Plot1 Off to open the P1 configuration
The cursor will be blinking on On. If not use cursor to highlight ON and press [ENTER]. The cursor will move to second line (TYPE), on first icon. Since you want to do a scatter PLOT that is the one to choose. Highlight it and press ENTER then move cursor with Down arrow to move to XList
If your data is in L1 and L2 Xlist and Ylist will be already selected. If you have entered your data in some other lists, enter the proper lists (L3,L4, etc.)

DRAWING THE SCATTER PLOT

Now you can press the [GRAPH] function key. Here is what you get

PERFORMING A REGRESSION

Because I chose it so, we will perform a quadratic regression QuadReg
To do so you press [STAT] and use right arrow to select the CALC(ulate) Menu. Type 5:QuadReg

Command echoes on Main screen as QuadReg with blinking cursor as above on the right.

If you press [ENTER] the calculator will assign L1 to X and L2 to Y by default. If that does not correspond to the problem, you had better change the names of the lists used by entering then explicitely on the command line. Just press [2nd][L1] then [2nd] [L2] to get the following screen

Pressing [ENTER] to execute the command will get you the regression equation and its coefficients but you will not be able to have it graphed on the scatter plot

The coefficient/factor of determination R2 is displayed if you ran the DiagnosticOn command from the catalaog, or as in the newer version of the OS (version 2.53MP) you press [MODE], scroll down to get to the second page of options and selected Stat Diagnostics ON

Thus to be able to draw the regression curve on the scatter plot, you must save it to a function variable, Y1 for example. You do it with the following command line

After you press ENTER you obtain the equation, a,b,c, and R2. By pressing the [GRAPH] function key you get the raw data and the regression on the same screen.

As you can see both are represented

TRACING THE REGRESSION CURVE
Press Trace and see what you get

As you can see the trace defaults to the scatter plot P1, L1,L2 (see the top left). If you stay on that graph you will on ly trace the actual data points (raw data). The cursor will jump from one point to the next.
To trace the regression curve (the second curve) you must move cursor on it. To do so press the Up and Down arrows. Left and right arrows allow cursor to move along the same curve.
Pressing Down Arrow you move to the regression curve. Notice the equation on the top left corner. The cursor can be displaced anywhere (depending on the resolution of the graph.

If you want Y for a particular value of X, just enter the value of X
Enter an X value. How about 5.55555?
Type in the value and press [ENTER] et voilà.

If as I have suggested above, you copied the regression equation to Y1 variable, you can calculate Y-values for any X in the graph domain.

In Main calculator screen type the numerical value of X, say 4.777756, and store it in X-variable

4.777756 [STO>] [X,T,theta,n] [ENTER]

Press [VARS][>][Y-VARS][1:Function...][1:Y1] [ENTER]

The calculator computes the value of Y1 for the entered value of X.
You can also generate a whole table, but you will have less control over the points where Y1 will be calculated.

Aug 24, 2010 | Texas Instruments TI-84 Plus Calculator

### How to Plot & graph or Model Quadratic on the same screen. I want to plot the points from adta table & then using Quad regression I got the equation ,but I can't graph on the same screen as the...

Read this post. It answers all your questions and shows you HOW to do find your equation of best fit, correlation coefficients, etc.

Before doing statistics, you have to prepare the calculator by clearing old data that may generate errors.

A. TO CLEAR OLD DATA
1. Press [2nd][+] (MEM) to open the memory management screen.
2. Press [4:ClrAllLists]
3. The command echoes on main screen, press [ENTER] to run it.
4. Calculator displays Done.
B. RUN the SETUP EDITOR Command
1. Press [STAT][5:SetUpEditor] [ENTER] ; calculator displays Done.
C. TURN DIAGNOSTICSON option (optional)

To obtain the correlation coefficient in a statistical analysis on the TI8xPlus family of calculators you must activate the DiagnosticsOn option. To access the command
1. You press [2nd] [0] (CATALOG)
2. While the list of commands is displayed, press [X^-1] (D)
3. Cursor jumps to first command that starts with D, dayOfWk(
4. Press the DownArrow 9 times to reach DiagnosticsOn
5. Select it and press [ENTER]
6. Command echoes on main calculator screen with blinking cursor
7. Press [ENTER] to set the option
8. Calculator displays Done.
From now on, if a correlation coefficient has meaning for a regression model, it will be calculated along with the other statistical results. If it has no meaning to the model it will not be calculated.

D. ENTER THE DATA
Press [STAT][1:Edit]
Type in your D (X ) values in L1 and the N (Y) values in L2 (see picture 1). Sorry the picture does not have YOUR values.

TO OBTAIN THE STATISTICAL RESULTS (optional)
1. After you finish entering the data, press [2nd][Quit] to exit StatEditor.
2. Press [STAT] and highlight Menu (CALC)
3. In the list select [2:2-Var Stats]
4. Command echoes on main screen.
5. Press [ENTER] to calculate the stats
Here is what you get (THESE~ARE NOT YOUR RESULTS). Your results will be different.

Notice the down arrow next to n=7. That means the results screen has more values. Press the down arrow to display.

You notice that the n=7 line now has an arrow pointing Up. Notice the Down Arrow on the bottom line (more data is coming). Here is the rest of the statistical results.

There is no arrow at the bottom of the picture. End of statistical results.
The screen captures with 2-Var Stats summarize all the satistics.

However there is no correlation coefficient, no line of best fit, etc. To obtain that you have to perform a regression analysis.

E. PERFORM A REGRESSION ANALYSIS
To perform a regression analysis, you must try several regression models and then find the one that mimicks the raw data best. In this particular case, you have already decided to do a linear regression, and that is good for me. I do not have the time to take you through all of them. In this step you must select the exponential regression model.
1. Press [STAT] , highlight [CALC]
2. In the list of regression models select [0:ExpReg]
3. The command ExpReg echoes on main calculator screen.
4. If you press [ENTER] you will get you equation but you will not be able to draw the curve on top of your data to verify the goodness (no it is not a swear word) of the fit. So you must save the equation as a function in Y1 variable.
5. While ExpReg command is still in command line, press the [VARS] key.
6. Highlight the [Y-VARS] menu and select [1:Function], then press [ENTER].
7. In the Y function variable list select [1:Y1]
8. At the command line, you have ExpReg Y1.
9. Press [ENTER] to save the equation of best fit in Y1.

You also have r and its square. You need to read your theory to know which of the two correlation coefficients you have been asked to obtain.

Since you saved the equation in the Y1 function you can draw it. You just have to press GRAPH and it will be drawn. But that will not tell how good the fit is, until you see the function drawn on top of the raw data.

DRAWING THE SCATTER PLOT AND BEST FIT CURVE ON SAME SCREEN

Regardless of the curve of best fit, you can draw a scatter plot as follows.
1. Press [2nd][Y=] (STATPLOT)
2. Select [1:Plot1...Off] and press ENTER to open plot1 configuration screen
3. Use arrow to highlight On and press ENTER
4. Use the down arrow to move cursor to the line Type.
5. Select the first icon for a scatter plot. NOTE: To navigate the 6 statistical stat plots on the line Type, use the right or left arrow (to backtrack), but not the Up or down arrows.
Here is the configuration screen

Here plot1 is active (ON), it is scatter plot (first icon) the Xlist is L1 by default but you can change it to some other list. Notice the highlighted A cursor on XLIST line. It means that the [ALPHA] keyboard is active.
On the line Mark you can choose the appearnce of the raw data point.

And here are your two graphs: the raw data scatter plot and the line of best fit on the same screen. On the picture the ZoomStat option was used.

Now, it is up to you to accept this model or to try another model.

Apr 16, 2010 | Texas Instruments TI-84 Plus Silver...

### How do u store linreg(ax+b)as y1 on ur graphic calculater

When you press [STAT] and right Arrow to highlight CALC you see two linear regression model [4:LinReg(ax+b)] and [8:LinReg(a +bx)]
If you select [4: ...] the command echoes on main calculator screen as LinReg(ax+b) and a blinking cursor
If you press [ENTER] you will get your equation, a, b, and r^2 if DiagnosticsOn command has been executed before. However you will not be able to see the line of best fit on top of the raw data scatter plot.

To save the equation of best fit in a function variable, ex Y1, you complete the command as follows
LinReg(ax+b) [VARS][=>][Y-VARS][1:Function][1:Y1]
The Y1 variable will appear on main calculator screen, and you have
LinReg(ax+b) Y1
Press [ENTER]
Screen display the equation, its parameter and its correlation coefficients (if so configured).
Press [GRAPH] to draw the line of best fit on top of the scatter plot.

Here are two screen captures to show you the equation and the line of best fit.

As you can see from the value of r^2, and the graph, a linear regression does not seem good.

Feb 01, 2010 | Texas Instruments TI-84 Plus Calculator

### Cannot graph invalid dim error

This error show up when you are graphing out of the plot menu. If you are not graphing data points from list menu, you need to turn the plots off. In the y= screen, you will see the words plot 1, plot 2, etc across the top of the screen. If one of the plots is highlighted (black box over the words), you need to turn it off. This can be done by arrowing up and highlighting the box and pressing enter. When you arrow back down, the plot should be off and you will be able to enter an equation in the y= lines and graph.

If you are graphing from the plot menu, this error lets you know that one of the lists you are graphing is longer than the other.

Another way to fix the problem is to reset the calculator by pressing 2nd button then plus sign then 7 then 1 then 2. This will reset the calculator however if you are graphing from lists, your data will be erased. Hope this helps.

Oct 02, 2009 | Texas Instruments TI-83 Plus Calculator

### INVALID DIM

on a calc that's work properly, in the 'y=' screen, none of the 'Plot#' things are highlighted. try pressing 'y=', and if you have a 'Plot#" in a black box, go up to it and press enter to un-highlight it.
either it will work as soon as you press 'graph',or you have another problem

Jan 19, 2007 | Texas Instruments TI-84 Plus Calculator

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