HP 15c Scientific x, x, Tn, x ≠, x ≥, x ≤, Test, Test, x = y, x ≠ y, x > y, x < y, x ≥ y, 2.Indirect: |Tn, conditional test, 1.Direct: |£and |

Section 8: Program Branching and Controls 91

of this loop can be controlled by a conditional branch, an ¦ instruction (written into the loop), or simply by pressing any key during execution (which stops the program).

Conditional Tests

Another way to alter the sequence of program execution is by a conditional test, a true/false test which compares the number in the X-register either to zero or to the number in the Y-register. The HP-15C provides 12 different tests, two explicit on the keyboard and 10 others accessible using

Tn.*1.Direct: £and ~.2.Indirect: Tn.

n	Test	n	Test
0	x ≠ 0	5	x = y
1	x > 0	6	x ≠ y
2	x < 0	7	x > y
3	x ≥ 0	8	x < y
4	x ≤ 0	9	x ≥ y

*Four of the conditional tests can also be used for complex values, as explained in section 11 on page 132.