I am hoping for some help to calculate the gradient of a dataset.
The data is the output from a datalogger that is connected to a weigher
The full dataset is approx 20,000 records (time and date vs weight of a
vessel)
The weight falls over time at a reasonably consistent rate as the contents
are used.
As the level gets low the vessel is quickly topped up.
Therefore is the full data is plotted the output is a rough sawtooth
profile.

I can use =LINEST(B1:B37,A1:A37) to give me the best fit gradient for the
first cycle
but as there are likely to be over 500cycles a manual method will be
tedious.
Plus I am likely to have 5 more datasets as part of this work.

The data is quite noisy so I have found spotting the start of a cycle
tricky.
The cycles are not a fixed length so this is another problem.

I would like to copy a formula down next to the data that will show a
value for the gradient once every cycle
leaving no value between.
But any way of more automatically picking out each cycle to apply the
formula would be a big help

I am using Excel2000 and am able to use VBA if necessary

Many thanks for taking the time to look at this

Cheers Rob

********************************************
Extract of data
06/07/2006 00:03:07 431.685
06/07/2006 00:04:07 433.305
06/07/2006 00:05:07 428.5425
06/07/2006 00:06:07 424.995
06/07/2006 00:07:07 420.24
06/07/2006 00:08:07 416.3625
06/07/2006 00:09:07 411.66
06/07/2006 00:10:07 407.205
06/07/2006 00:11:07 402.75
06/07/2006 00:12:07 398.1675
06/07/2006 00:13:07 394.05
06/07/2006 00:14:07 389.805
06/07/2006 00:15:07 385.53
06/07/2006 00:16:07 380.985
06/07/2006 00:17:07 376.1325
06/07/2006 00:18:07 371.52
06/07/2006 00:19:07 366.7875
06/07/2006 00:20:07 361.2
06/07/2006 00:21:07 357.2925
06/07/2006 00:22:07 352.6575
06/07/2006 00:23:07 347.5275
06/07/2006 00:24:07 342.915
06/07/2006 00:25:07 338.25
06/07/2006 00:26:07 333.4275
06/07/2006 00:27:07 329.025
06/07/2006 00:28:07 324.45
06/07/2006 00:29:07 319.47
06/07/2006 00:30:07 315.0225
06/07/2006 00:31:07 309.645
06/07/2006 00:32:07 305.28
06/07/2006 00:33:07 300.795
06/07/2006 00:34:07 296.1525
06/07/2006 00:35:07 291.09
06/07/2006 00:36:07 286.4775
06/07/2006 00:37:07 281.3175
06/07/2006 00:38:07 278.325
06/07/2006 00:39:07 272.25
06/07/2006 00:40:07 267.3675
06/07/2006 00:41:07 370.1475
06/07/2006 00:42:07 433.1175
06/07/2006 00:43:07 428.235
06/07/2006 00:44:07 423.6525
06/07/2006 00:45:07 419.505
06/07/2006 00:46:07 413.9775
06/07/2006 00:47:07 409.2225
06/07/2006 00:48:07 404.9475
06/07/2006 00:49:07 399.7275
06/07/2006 00:50:07 395.205
06/07/2006 00:51:07 390.63
06/07/2006 00:52:07 385.9575
06/07/2006 00:53:07 380.985
06/07/2006 00:54:07 376.1625
06/07/2006 00:55:07 372.0375
06/07/2006 00:56:07 366.7575
06/07/2006 00:57:07 361.6575
06/07/2006 00:58:07 357.33
06/07/2006 00:59:07 352.17
06/07/2006 01:00:07 348.105
06/07/2006 01:01:07 343.3425
06/07/2006 01:02:07 339.465
06/07/2006 01:03:07 334.83
06/07/2006 01:04:07 330.1275
06/07/2006 01:05:07 326.685