Working with PTC Mathcad Prime > Working with Math Expressions > Evaluating Math Expressions > About Evaluating Math Expressions
  
About Evaluating Math Expressions
PTC Mathcad evaluates math expressions in a left-right, top-down order. When you change a math expression, its result is updated automatically. All the dependent math regions to the right or below the changed expressions are updated accordingly. If you disable region calculation, the results are not updated.
If you need to evaluate an expression or function repeatedly, you can use a range variable or a vector. You can store results by writing them to a file, or copying and pasting them.
There are four fundamentally different types of equal signs in PTC Mathcad:
Definition operator—Defines variables and functions.
Evaluation operator—Evaluates an expression.
Equal to operator—Compares variables, vectors, or expressions. Use this operator in Boolean expressions or constraints for solve blocks.
Local range variable definition operator—Defines the range variable for the sum or product operator.
Make sure any variables you use in the expression to the left of the evaluation operator are defined. You can trace errors to understand where an error originated. You can adjust the result display to show greater precision or a different numerical format. You can also change the units of the result.