
Circles and Lines: The Quick Calculator
10 Mar, 2006 By: Lynn Allen CadalystAutoCAD's new Quick Calculator feature is a powerful tool for your mathematical calculations.
Let's face it: most of us don't like math. We avoided it in school, cringed at the thought of going to math class and yet are still confronted with mathematical situations every day of our lives. The world of AutoCAD is no exception because we're dealing with geometry 24/7. You just might find the Quick Calculator can help you with some of those dreaded math encounters and even speed up some of your everyday practices. Wouldn't that be nice?
QuickCal
For years, many of us used a topsecret function called CAL. CAL allowed us to perform mathematical and geometric functions inside and outside of commands. The new Quick Calculator (QuickCalc command) in AutoCAD 2006 set out to take that powerful tool and provide a friendly user interface. For those of you who haven't made it up to AutoCAD 2006 yet, you might just want to give the old CAL command a try.
Figure 1 shows the shiny new Quick Calculator. A first glimpse might lead you to believe it's just an ordinary calculator, but it's much more. Hidden inside this cool feature is the ability to make units conversions (metric to imperial, for example) as well as some nifty geometric shortcuts you'll drool over once you discover them. Let's take the grand tour.
Figure 1. The new Quick Calculator is much more than an everyday calculator. 
You can easily get to the Quick Calculator by selecting the icon on the standard toolbar. You'll also find that if you're in a numeric field in the Properties palette (figure 2), the Quick Calculator image will display, making it easy to pop into the calculator for a quick calculation. Because it is transparent, you can access it from the Command prompt or within a command.
Figure 2. You can easily access the Quick Calculator from a numeric cell in the Properties palette. 
Quick Tools
At the very top of QuickCalc is a toolbar for quick access to some powerful tools.
Figure 3. The Quick Calculator toolbar. 
The first tool with the eraser quickly clears the input box. The second tool clears the history area as well. (You'll notice that QuickCalc records all input and saves it to a history should you choose to use one of the values later.) The third tool, which looks like a paste icon , takes the value from the input box and pastes it to the Command line for use in an existing command.
The icon with the little red X is used to return the x,y z coordinates of any point you select in the drawing. This feature is available only at the Command prompt.
The ruler icon makes it easy to quickly calculate the distance between two points either on or off an object (the Help file indicates the points must be on an object). The angle icon lets you select any two points and return the angle. The icon of the large X is used to calculate the intersection of four points (imagine two lines crossing). I think it would be just as easy to use the point option and select the intersection if the lines already exist. And last, but not least, the valuable Help option will walk you through this process until you feel comfortable with the commands.
Below these tools is the history area that records the input values until you clear it. A rightclick in the history area allows you copy one of the values to the Command line (figure 4).
Figure 4. The History shortcut menu has several options that let you use the previous input values. 
Below the history is a standard calculator configuration along with a few bonus tools. Most people use this section because few have toured the other powerful capabilities. It works as you'd expect it to work. It includes a few nice exponential options for quick access as well as a squareroot option.
The scientific section is for you diehard math buffs who need trigonometric, logarithmic and other expressions. I will save you the agony of pouring over this section in detail because I realize that those of you who need this capability already fully understand it (right?). You will find a nice R2D function that converts radians to degrees for you LISPers and vice versa (D2R) for degrees to radians. You can also round off the number in the input box to the nearest integer by using the MD function.
Units Conversion
I find the units conversion area useful because I spend so much time going back and forth between metric and imperial with my travels. The key to using this section is to use only decimal values and not include any unit symbols such as the apostrophe to indicate feet or the double quote to indicate inches. I'll be the first to admit this section is a little cumbersome to use. For example, if you want to convert 6' 3" to meters, you need to first convert it to inches (75) and input the value 75 for the conversion. These steps might drive you a little crazy.
The last section  variables  is powerful, but it takes some time to figure out. Some handy geometric expressions might come in useful as you are designing. For example, perhaps you'd like the center of a circle to be placed at the midpoint between two line end points (MEE function). You could, of course, draw a construction line to figure that location out  or you can use the Quick Calculator to do it.
The process goes like this: Select the expression you want to use, rightclick and select Return to the Input Area. Your expression will appear on the input line of the dialog box. Making sure you are at the Command prompt (not in a command), place the cursor on the expression line and hit Enter. AutoCAD will ask you to select the two end points and return the midpoint value to you. Next, enter the Circle command and paste the coordinate value to the command. This process is somewhat cumbersome but doable. You can add your own expressions, save variables, etc., in this section. And here's the kicker  variables you save here will follow you to other drawings for future use! Now that can come in handy.
Let's review some of the existing expressions:
DEE Distance between two end points
ILLE Intersection of two lines defined by four end points (just use the toolbar option instead  much faster)
MEE Midpoint between two end points (which you can also get to by using the M2P osnap instead with less headache)
NEE The normal between to end points
Rad Radius of a circle, arc or polyline arc
VEE Vector from two end points
VEE1 Unit vector from two end points
Yikes, some of these options are mighty scary !
So as you can see, there is much more to Quick Calculator than meets the eye. I look forward to more improvements to the Quick Calculator command in the future to make it a little less processoriented and a little friendlier, but in the mean time give it a try!

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