Kalevipoeg , thank you! This is brilliant. Lines 12-24 create the VV.0hhh very elegantly. Also I believe you are the first to calculate the correct crash velocity when the first iteration gives a new height as negative - you reverse time and bring us back to the surface with the correct speed!! Please move onto Tic-Tac-toe now:-)

Gene's page has an ingenious program that uses 3 by 3 magic square space to facilitate win/block calculations.

Cheers,

Tony

Slightly less intense digit,.,EEX, alternatives might be:

5 lines 14-18: RCL1 % % RCL2 X<>Y

12 lines 44-55: ENTER + 5 - STO4 RCL2 X<>Y STO+2 2 / + STO+1

One could even shave 1 line off this, if I count correctly<G>:

STO4 STO+4 5 STO-4 RCL2 RCL4 STO+2 2 / + STO+1

Down to 78 lines and falling<G>. This is fun. From the quality of your code and clarity of exposition I feel I know you from somewhere ;-)

Now I'm onto my third edit. It seems possible to remove more lines by allowing an empty craft to recycle once more. One could have 5 chs sto4 up at line 12. Then we can remove the 5 sto-4, and change the start to STO+4 STO+4 above in my last feeble attempt to shave lines - but that part is now down to 9 where it was 12.

Instead we can do the rcl3 x=0? test by "inserting" x=0 gto "67" after the rcl 3 at line 39.

Overall this may save us another 3 lines, but I admit the operation will be slightly different - we get to "see" an empty craft just one more time before the free-fall with R4=-5. Of course we could save another 2 by not testing for R3=0 at all - just keep seeing the free-fall second by second until we go underground at the end :-)

But that is too slow ... although one can burn the 60 and see oneself travel out into space before returning. But, too slow to watch. The best place for the R3=0 test is probably after it is displayed - before the burn count-down - then one at least gets to see the final VV.0hhh begore the free-fall. Yup, it seems to work fine here at 75 lines. Good night all. Thanks for the fun :-)

Here it is, in case anyone wants to try/tweak/untweak it.

Thanks again to Kalevipoeg - whoever he/she is - maybe an ex-astronaut :-) And also thanks to Gene for these game challenges.

Keystrokes |Display | Comments

[f][P/R] | |

[f]CLEAR[PRGM] |00- |

5 |01- 5 |

0 |02- 0 |

0 |03- 0 |

[STO]1 |04- 44 1 | h=500ft

5 |05- 5 |

0 |06- 0 |

[CHS] |07- 16 |

[STO]2 |08- 44 2 | V=-50ft/sec

6 |09- 6 |

0 |10- 0 |

[STO]3 |11- 44 3 | Fuel=60

5 |12- 5 |

[CHS] |13- 16 |

[STO]4 |14- 44 4 | accel=-5ft/sec/sec

1 |15- 1 |

[CHS] |16- 16 |

[RCL]1 |17- 45 1 |

[%] |18- 25 |

[%] |19- 25 | +hE-4=.0hhh

[RCL]2 |20- 45 2 |

[x<>y] |21- 34 |

[-] |22- 30 |

[g][x<=y] |23- 43 34 |

[g][GTO]28 |24- 43,33 28 |

[RCL]2 |25- 45 2 |

[g][LSTx] |26- 43 36 |

[+] |27- 40 |

[f]4 |28- 42 4 |

[g][PSE] |29- 43 31 | VV.0hhh

[g][PSE] |30- 43 31 |

[RCL]3 |31- 45 3 | Fuel

[f]0 |32- 42 0 |

[g][PSE] |33- 43 31 |

[g][x=0] |34- 43 35 | no fuel left?

[g][GTO]63 |35- 43,33 63 | free fall

3 |36- 3 | count down

[g][PSE] |37- 43 31 |

2 |38- 2 |

[g][PSE] |39- 43 31 |

1 |40- 1 |

[g][PSE] |41- 43 31 |

0 |42- 0 |

[g][PSE] |43- 43 31 |

[RCL]3 |44- 45 3 |

[g][x<=y] |45- 43 34 |

[x<>y] |46- 34 |

[RDN] |47- 33 |

[STO][-]3 |48- 44 30 3 | update Fuel

[STO][+]4 |49- 44 40 4 | update

[STO][+]4 |50- 44 40 4 | acceleration

[RCL]2 |51- 45 2 |

[RCL]4 |52- 45 4 |

[STO][+]2 |53- 44 40 2 | update V

2 |54- 2 |

[/] |55- 10 |

[+] |56- 40 |

[STO][+]1 |57- 44 40 1 | update h

0 |58- 0 |

[RCL]1 |59- 45 1 |

[g][x<=y] |60- 43 34 | underground?

[g][GTO]63 |61- 43,33 63 | 're-calc' crash velocity

[g][GTO]12 |62- 43,33 12 | burn again

[RCL]2 |63- 45 2 |

[ENTER] |64- 36 |

[x] |65- 20 | v0^2

[RCL]4 |66- 45 4 |

[RCL]1 |67- 45 1 |

[x] |68- 20 |

[ENTER] |69- 36 |

[+] |70- 40 | 2*a*h

[-] |71- 30 |

[g][SQRT] |72- 43 21 |

[CHS] |73- 16 | V at h=0

[g][PSE] |74- 43 31 |

[g][GTO]74 |75- 43,33 74 |

[f][P/R] | |

To find a final free-fall time in seconds, stop &:

[RCL]2 [-] [RCL]4 [/]

eg, if all 60 is burnt on first cycle, we obtain a final crash v of

-96ft/sec and time=32 sec. This is the longest trip and worst

crash :-)

*Edited: 5 Oct 2005, 7:09 a.m. *