How to enter formulae
Formula can be entered for most fields for the product library, part library, machining instructions, and drawing library. Move to the field and enter the formula
Formula start with an = sign
ALL formula start with the '=' symbol
=X+5.0 - Y/2+3
At the product library, machining library and drawing library screens the formula is automatically evaluated and shown in a status bar at the foot of the screen.
Standard arithmetic
Use standard arithmetic operators for relating variables.
+ add
- subtract
/ divide
* multiply
() brackets
The operators are evaluated in the usual order, that is, * / + -, for example:-
10 + 30/2 = 25
Use brackets to clarify complex definitions.
(10 + 30)/2 = 20
Use the pre-defined variables for product and part dimensions.
X - overall product width
Y - overall product height
Z - overall product depth
=X/2 + Y/4
Enter constants as ordinary numbers. These are interpreted exactly as entered:-
=X/2 + Y/4 + 25.5
Predefined formulae
Fx $ @ - Use these options to add predefined formula, variables or look-up items to a field or to extend an existing formula. A button is greyed out where it does not apply to a field.
Complex formulae
Some formula can be quite long - use the cursor keys to scroll through the box to see the full formula. At the Formula table press F2 display the formula in a pop-up dialog.
Inches and minus sign
Inches - some confusion can arise because the minus sign (hyphen) is also used to separate inches and fractions:
23-1/2
To enter a fractional value use the inches function F, which stands for fractional inches:-
F(23-1/2)
Alternatively enter the value in decimal inches: 23.5
Fractional inches and constants
Constants and fractional inches - When using fractional inches the difference between a constant 12-1/2 and a formula =12-1/2 is significant. The constant is evaluated to 12.5 but the formula is evaluated to 11.5. (In millimetres, for example, 12.5 and =12.5 both evaluate to a value of 12.5.
Using the formula table - this is a table of pre-defined formula. So complex formula can be associated with a simple name. For example:-
XBORE: X start for shelf holes: (X-18)+3
YBORE: Y start for shelf holes: (Y-24)+6
TB formula name can then be used in place of the actual formula.
xStart &XBORE&
yStart &YBORE&
This helps to make the instructions clearer, easier to enter, and less prone to error. It also allows use of a single formula where the same formula occurs in several different situations.
Notes
- In some cases the formula cannot be evaluated instantly because it depends on the product dimensions or variables that are not in the variables table or a suitable default is not set for the variable.
- When evaluating a formula if the formula contains a variable and the default variable answer is used and this is blank a value of 0 is assumed.
