README file for maf_cub.c
(C)2002 Perry Harrington <pedward at dainst.com>

How to use

The program takes 4 command line arguments:  input point count, output point count,
output min voltage, and output max voltage.

input point count is the number of points in your input data file
output point count is the desired number of data points to generate from the input data
output min voltage is the min x value to output for the generated data points
output max voltage is the max x value to output for the generated data points

Dataset

The only "RULE" about the dataset is that it MUST be ordered.  ALL your X values must
be in numerical order from LEAST to GREATEST.  If you do not order your dataset, the
program will emit an error to inform you.  If you are rearranging numbers to make them
compatible with the input format, it's easy to accidentally mess up the X order.

The input dataset can be massaged to produce a desired output dataset.  If you are
generating a zero based output dataset (where the vmin is 0.0) then you will likely not
want any negative output values.  To ensure this, make the first line of your input file
'0.0, 0.0' without the quotes.  As you see in the dataset below, that is what I did to
get non-negative results.

If you are using the program for general interpolation, like for an NTC thermistor, you don't
need to massage the input data.  There is an example below showing such an application.

Piping

This program is designed to work as a filter and can have data piped to and from it.  Only the dataset
and tag names appear on STDOUT.  The input verification data is on STDERR.  Input data is fed
in STDIN.

Examples

Here is an example for generating a MAF flow table using the 10 points
on the calibration sheet that Pro-Flow shipped with my MAF.

[pedward]$ cat maf_data.txt
0.0, 0.0
0.016, 0
0.302, 10.3
0.537, 17.2
0.917, 34.4
2.436, 199.1
3.422, 453.2
3.860, 601.5
4.393, 853.0
4.513, 901.1
4.907, 1150.0

[pedward]$ ./maf_cub 11 30 0.0 5.0 < maf_data.txt 
vmin = 0.000000 vmax = 5.000000 step = 0.172414 points = 30
/* ( Voltage, Flow ) */

( 5.0000, 1217.4816 )	( 4.8276, 1092.6801 )	( 4.6552, 976.9308 )	
( 4.4828, 888.2458 )	( 4.3103, 817.7397 )	( 4.1379, 734.7899 )	
( 3.9655, 649.4869 )	( 3.7931, 574.1686 )	( 3.6207, 513.3171 )	
( 3.4483, 460.8804 )	( 3.2759, 410.8358 )	( 3.1034, 362.0396 )	
( 2.9310, 315.2585 )	( 2.7586, 271.2638 )	( 2.5862, 230.8270 )	
( 2.4138, 194.7188 )	( 2.2414, 163.4087 )	( 2.0690, 136.5423 )	
( 1.8966, 113.6258 )	( 1.7241, 94.1654 )	( 1.5517, 77.6674 )	
( 1.3793, 63.6379 )	( 1.2069, 51.5832 )	( 1.0345, 41.0094 )	
( 0.8621, 31.4316 )	( 0.6897, 22.9519 )	( 0.5172, 16.6175 )	
( 0.3448, 11.8453 )	( 0.1724, 4.4119 )	( 0.0000, 0.0000 )	

Here is an example for generating a complete table of resistance values
for an NTC thermistor.  The datasets are Temp, Resistance.  

[pedward]$ cat res1.txt
6.8, 10700
44.6, 5700
55, 3310
58, 3250
71, 2240
80, 1820
91, 1470
109, 1020
114, 900
138, 470
165, 330
170, 310
179, 260

[pedward]$ ./maf_cub 13 15 -40 210 < res1.txt 
vmin = -40.000000 vmax = 210.000000 step = 17.857143 points = 15
/* ( Voltage, Flow ) */

( 210.0000, 73.6395 )	( 192.1429, 180.9900 )	( 174.2857, 287.7505 )	
( 156.4286, 357.1371 )	( 138.5714, 463.9298 )	( 120.7143, 750.3044 )	
( 102.8571, 1164.7104 )	( 85.0000, 1657.1409 )	( 67.1429, 2590.0137 )	
( 49.2857, 4356.9180 )	( 31.4286, 8502.7588 )	( 13.5714, 10294.7158 )	
( -4.2857, 11336.8848 )	( -22.1429, 12362.7959 )	( -40.0000, 13388.7061 )