Basic Instructions for Winplot
Getting Started:
When you first enter Winplot, you want to go to “Window”, then “2-dim”. A 2-dimensional grid
should appear.
The “page up” and “page down” buttons on your key board should allow you to zoom in on the
grid, or zoom out.
Be sure to go to “File” and “Save as” right away. This is a free download, so it does come with
some issues! You will want to save often in case the program spontaneously closes.
Entering Equations in Winplot:
When you are ready to enter an equation, you will pull down the menu under “Equa” (equation)
There are 3 options that we will be working with:
1. Explicit
2. Implicit
3. Segment
Explicit form is used to enter an equation in y=____ form. When you open the explicit option,
the following example will pop up: “f(x)=xsin(x)”. You should delete “xsin(x)” and type in your
equation and click “ok”.
Implicit form is used to enter an equation that does not have y isolated. For example, a circle:
x 2  y 2  4 . When you select implicit from the “Equa” menu, a sample equation will appear:
xx+yy=13. xx represents x squared, and yy is y squared. You can delete the sample equation
and type in your own. Then, click “ok”. If you need to graph part of an ellipse, circle,
hyperbola, line etc., you must rewrite the equation in explicit form.
If you need to graph a vertical line, you must use Implicit form. (Recall that a vertical line is
x=___.) However, if you need to graph a portion of a vertical line, you will have to use the
segment feature in Winplot.
The Segment feature draws a segment between 2 points on your grid. You enter the two
points, click “ok”, and Winplot will connect them. You are only allowed to use the segment
feature for vertical lines. In the Equa menu, scroll down to Segment, then (x,y). The segment
box will appear. You can enter the coordinates of the two points that you would like to connect
to form the vertical line segment. x1 and y1 represent the first point, and x2 and y2 represent
the second point. Again, you may only use the segment feature to graph a vertical line
segment. All other lines should be graphed using explicit or implicit form.
Editing Equations/Equation Inventory:
Each equation that you enter should appear in the “inventory”. If the inventory box does not pop
up automatically, you can open it by typing control+i, or go to the “Equa” menu and select
“inventory”. If you want to go back and revise an equation, open the inventory menu and double
click on the equation, or highlight the equation and click “edit”
You can change the width of the lines and curves in the Explicit, Implicit, and Segment boxes.
“Pen width” appears in each of the boxes; the default setting should be 1. If you need to make
any of the lines and curves thicker, then you can choose a number greater than 1. You can also
change the color of the lines using the “color” feature, but this is not required for the project.
Graphing Partial Curves:
If you want to graph a portion of a line (non-vertical), circle, ellipse, parabola, or hyperbola, the
equation must be graphed in explicit form. This can be a difficult task if you are working with
an ellipse, circle, parabola, or hyperbola. Look at your sketch on the graph paper and decide
where you need to cut off the graph. More specifically, you need to decide on the domain for
that equation. (Recall that domain includes the possible x-coordinates.) The smallest x-value
and largest x-value in your domain need to be entered in the explicit box. In the explicit box,
enter the smallest x-value next to “low x” and the highest x-value next to “high x”. You also
need to check the box labeled “lock interval”. Then, click “ok”. See the example below.
This is a graph of the line y = x – 2. However, only a portion of the line is graphed below. The
domain only includes x-coordinates between -1 and 2. Therefore, the smallest value for x is -1
and the largest value is 2. See the explicit box from Winplot below.
y

x










When converting an ellipse, parabola, circle, or hyperbola to explicit form, it may be necessary
to use a square root. In Winplot, square root is “sqrt”. For example, let’s graph the lower half of
a circle.
2
2
 x  2    y  4   25 Start with standard form for the circle.
 y  4
2
 25   x  2 
2
y  4   25   x  2 
y  4  25   x  2 
y  4  25   x  2 
2
Explicit form requires you to isolate y.
Take the square root of both sides of the equation.
Don’t forget the + or -.
2
2
The positive square root will graph the top half of the
circle. The negative square root will graph the
bottom half of the circle.
Notice that square root in
Winplot is “sqrt”. Use “sqrt”
with parentheses. Also, the ^
is used to raise quantities to a
higher power.
Now, let’s say that I changed my mind and only want the lower right quarter of the circle on my
graph. I will then change the domain to only extend from -2 to 3.
Don’t forget to “lock interval”
when you restrict the domain
of a curve.
Printing:
When you are ready to print, go to “File”, then “Print”. However, it is likely that your picture will
come out very small. If this happens, go to “File”, then “Format”. Change the width to
approximately 15-20 centimeters, then print. You may need to use the “Page up” or “Page
down” buttons on your key board to zoom in or out of your picture prior to printing.
To assist you in typing your inventory,you can also copy and paste your inventory into a Word
document. In the inventory box, you can highlight an equation, click on “clip”, then paste the
equation in a Word document. Remember they must be copied one at a time.
Hints:
1. Make sure if you change computers the versions of Winplot are the same.
2. After saving a file, to re-open it, first open Winplot. Then select file, open to gain access to
your Winplot file.
3. If Winplot says “too many equations,” then save your file, close Winplot, and re-open Winplot
and your file.
4. Do not wait until the last minute to complete this project!!
alg2frWinplotInstruc