Program Loops

A loop is a block of code that causes one or more statements (the body of the loop) to iterate until a termination condition occurs. There are two kinds of loops:

For loops are used when you know exactly how many times the body of the loop should execute.
While loops are used when you want to stop execution upon the occurrence of a condition but you don't know exactly when that condition will occur.

For Loops

Keystroke: [Ctrl] " Do not type the word "for." It does not produce the operator.

Evaluates z for each value of x over the range y. Typically, at least one expression in the loop body, z, uses the value of x to change the calculation for each evaluation. Use a for loop when you know exactly how many times you want the body of the loop to execute.

Operands:

x is any valid Mathcad variable name.
y is a value or sequence of values. Most frequently, this is a range value, but you can also use a vector, or a comma-separated list of scalars or vectors, each of which results in a series of scalar values to be assumed by the iteration variable x. y can also be a series of matrices, separated by commas; x assumes the value of each matrix in turn. This is a convenient way to apply the same calculation to a set of matrices.
z is any valid Mathcad expression or sequence of expressions. For example, a local assignment, or a sequence of programming steps is allowed here. Use the Add Line operator to insert placeholders for additional statements.

Example:

Notes:

When you use a for loop, you must know the number of times you want the loop to execute; the final result of the iteration is not important.
You may want to exit a loop before its termination condition is met, or skip a particular iteration and proceed to the next one. You can control the execution of either type of loop by using the break and continue operators.

QuickSheet

While Loops

Keystroke: [Ctrl] ] Do not type the word "while." It does not produce the operator.

Evaluates y while x is nonzero (true). The condition expression is evaluated at the beginning of the while loop, so it is possible that the loop never executes. The loop stops iterating as soon as the condition is false and returns the last value calculated in its body on the previous iteration.

Operands:

x is any valid Mathcad expression or sequence of expressions that can evaluate to 0, frequently a boolean expression.
y is any valid Mathcad expression or sequence of expressions. At least one expression in the loop body must change the condition expression, x, so that it becomes false; otherwise, the loop executes indefinitely and you need to stop it by pressing [Esc]. Use the Add Line operator to insert placeholders for additional statements.