HP 33s hp 33s_user's manual_English_E_HDPM20PIE56.pdf - Page 202

Loops with Counters (DSE, ISG) When you want to execute a loop a specific number of times, use the { l (increment; skip if greater than) or | m (decrement; skip if less than or equal to) conditional function keys. Each time a loop function is executed in a program, it automatically decrements or increments a counter value stored in a variable. It compares the current counter value to a final counter value, then continues or exits the loop depending on the result. For a count-down loop, use | m variable For a count-up loop, use { l variable These functions accomplish the same thing as a FOR-NEXT loop in BASIC:  variable = initial-value ! final-value . . . ! increment %! variable A DSE instruction is like a FOR-NEXT loop with a negative increment. After pressing a shifted key for ISG or DSE ( { l or | m ), you will be prompted for a variable that will contain the loop-control number (described below). The Loop-Control Number The specified variable should contain a loop-control number ±ccccccc.fffii, where: „ ±ccccccc is the current counter value (1 to 12 digits). This value changes with loop execution. „ fff is the final counter value (must be three digits). This value does not change as the loop runs. „ ii is the interval for incrementing and decrementing (must be two digits or unspecified). This value does not change. An unspecified value for ii is assumed to be 01 (increment/decrement by 1). Given the loop-control number ccccccc.fffii, DSE decrements ccccccc to ccccccc - ii, compares the new ccccccc with fff, and makes program execution skip the next program line if this ccccccc ≤ fff. 13-18 Programming Techniques