## 20 Reputation

12 years, 158 days

## "Dual" command in Logic package...

Maple 18

Dear all,

I do not understand the output of the "Dual" command in the Logic package.

According to the help:

"The Dual command returns the dual of the Boolean expression b, that is, the expression generated by replacing &and with &or, &or with &and, leaving &not fixed, and extending to the remaining Boolean operators by their formulas in terms of &and, &or, and &not."

Applying Dual to "a &implies b" gives:
`Logic:-&implies`(`&not`(a), `&not`(b))

But "a &implies b" is equivalent to "&not(a) &or b" and its Dual would be "&not(a) &and b", which is not equivalent to the result Maple returns.

Best regards,
Anthei

## weighting scheme for LinearFit() and Non...

Maple

Can you please tell me the exact weighting scheme for LinearFit() and NonlinearFit() when using the weights= option?

Is it wi*(yi_exp-yi_calc)^2 or wi^2*(yi_exp-yi_calc)^2 ?

(wi=weight of point i, yi_exp=value i measured, yi_calc= value i calculated from the model function)

Best regards,

Anthrazius

## How to correctly apply windowing in Sign...

Maple 18

I am trying to apply window functions from the SignalProcessing package to arrays. However, some window functions (e.g. Hann) appear to operate on a [0..N-1] index basis, others (e.g. Welch) work on [1..N].

I don't know how to make the latter ones work correctly, since after applying the windowing function the first entry in the array is not zero, as it should be.

Best regards

## densityplot as background...

Maple 15

I have a problem with animations using a density plot as background.

The density plot covers the animation.

Here is an example:

plt:=densityplot(-(x^2+y^2),x=-1..1,y=-1..1);
animate(plot,[[sin(r)*cos(t),sin(r)*sin(t),t=0..2*Pi],thickness=10],r=0..Pi,background=plt);

Can this be solved?

Best regards

anthei

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