Driving parameter values

Parameters are often interdependent, with one parameter driving the value of one or more other parameters. For example, if you dimension the three angles of a triangle, the first two angle dimensions are locked and the third is derived from the value of the first two angles. You can change the derived dimension only by changing one of the locked dimensions. Furthermore, if you constrain the three dimensions to be equal, they will all become derived, because the only solution is 60.

The lock status of a parameter that is dependent upon, or driven by, another parameter is shown as derived in the parameter table, and the driving parameter is shown as locked . If you unlock the driving parameter, it will also unlock the derived parameter, allowing you to change which parameter drives the other. (See Locking and unlocking parameters.)

The concept of driving parameters is the same for variables set by equations as it is for geometric dimensions. You can use any parameter value in an equation to drive the other values in that equation.

For example, in the equation A+B=C, if you enter a value for A and B, they will be locked and C will be derived. C is not modifiable, because it is set by the values for A and B, which were entered first.

If you unlock A and/or B, the lock status for C will change from derived to unlocked. Unlocked parameters indicate that their values are modifiable.

You can then enter a value for any unlocked variable(s) to drive the remaining values in the equation. In this example, all values were unlocked, then values were entered for B and C, which now drive the value for A.