polyderiv problem?

[Joe Koski]

When doing a larger script, I had this problem. Here is the short version of
what happened.

If I run the simple script:

function run_poly_test
x = [1:5]
y = rand(1,5)
n=3
[coeff,mat] = polyfit(x,y,n);
coeff
d_coeff1 = polyderiv(coeff')
d_coeff2 = polyderiv(coeff)

I get the following output:

octave:4> run_poly_test
x =

  1  2  3  4  5

y =

  0.15180  0.69255  0.77507  0.26829  0.58182

n = 3
coeff =

   0.10655
  -1.03346
   3.00537
  -1.94867

d_coeff1 =

   0.31964  -2.06693   3.00537

error: product: nonconformant arguments (op1 is 3x1, op2 is 1x3)
error: evaluating binary operator `.*' near line 91, column 20
error: evaluating assignment expression near line 91, column 5
error: called from `polyderiv' in file
`/usr/local/share/octave/2.1.64/site/m/octave-forge/FIXES/polyderiv.m'
error: evaluating assignment expression near line 8, column 10
error: called from `run_poly_test' in file `/Users/jakoski/Codes/octave test
files/run_poly_test.m'
octave:4> 

In other words, I need to transpose the output coefficients from polyfit
into a row vector before they will work with polyderiv. This is on a Mac
running OS X 10.3.7 with octave 2.1.64.

Is this a MATLAB compatibility "feature," a bug, or am I missing something?

Joe




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