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I've had a lot of visitors but few comments! Let me hear from you! **Email me at:**
Genewright143@hotmail.com

This program originally appeared in the January 1980 PPC Journal V7N1 by Charles Hooper. Thanks to Charles wherever he is today! This program uses the HP-34C's built-in linear regression for fitting straight lines and adds the possibilities of exponential, logarithmic, and power curve fits.

**Instructions:** 1) Clear registers. f REG. 2) Key data to be entered as X ENTER Y and
press A. Display shows the number of data points entered. 3) If you make a mistake in step
2, immediately re-enter the incorrect pair and press R/S. Display will show one less data
point entered. 4) Turn the machine off then back on to initialize flags. This
will set the machine to linear regression status. 5) For exponential curve fits, press GSB
1. Display will show a 1. 6) For logarithmic curve fits, press GSB 2. Display will show a 2.
7) For power curve fits, press GSB 3. Display will show a 3. 8) Determine the "goodness" of
fit by calculating the correlation coefficient. Press h r. Display shows
the correlation.
(My statistics
teachers would
say square this
number to show
the total
variation
explained by the
model, but then
again, I'm not in
school any
longer). 9)
Extrapolate points
using the equation
by entering X and
pressing the B
key. Display
shows the
projected Y value.

To try a different model, turn the calculator off then on again and go to step 5, 6, or 7 above.

Line Instruction 01 h LBL 0 02 h SF 0 03 h LBL A 04 STO I 05 f LN 06 GSB 4 07 STO+ 8 08 g X^2 09 GSB 4 10 STO+ 9 11 X <> Y 12 STO. 3 13 f LN 14 GSB 4 15 STO+ 6 16 g X^2 17 GSB 4 18 STO+ 7 19 RCL. 1 20 RCL I 21 h LASTX 22 * 23 + 24 STO. 1 25 RCL. 2 26 RCL I 27 f LN 28 RCL. 3 29 * 30 GSB 4 31 + 32 STO. 2 33 RCL. 0 34 RCL. 3 35 f LN 36 RCL I 37 f LN 38 * 39 GSB 4 40 + 41 STO. 0 42 RCL I 43 RCL. 3 44 h F? 0 45 GTO 5 46 f SIGMA+ 47 h RTN 48 h LBL 4 49 h F? 0 50 CHS 51 h RTN 52 h LBL 5 53 f SIGMA- 54 h CF 0 55 h RTN 56 h LBL B 57 h F? 2 58 f LN 59 h Y-HAT 60 h F? 1 61 f LN 62 h RTN 63 h LBL 3 64 GSB 1 65 GSB 2 66 RCL. 0 67 RCL. 2 68 STO. 0 69 CLX 70 RCL 5 71 STO 1 72 X <> Y 73 STO 5 74 3 75 RTN 76 h LBL 2 77 h SF 2 78 RCL 6 79 RCL 1 80 STO 6 81 X <> Y 82 STO 1 83 RCL 7 84 RCL 2 85 STO 7 86 X <> Y 87 STO 2 88 RCL. 1 89 RCL 5 90 STO. 1 91 X <> Y 92 STO 5 93 2 94 h RTN 95 h LBL 1 96 h SF 1 97 RCL 3 98 RCL 8 99 STO 3 100 X <> Y 101 STO 8 102 RCL 4 103 RCL 9 104 STO 4 105 X <> Y 106 STO 9 107 RCL. 2 108 RCL 5 109 STO. 2 110 X <> Y 111 STO 5 112 1 113 h RTN

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