dharr

Dr. David Harrington

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20 years, 338 days
University of Victoria
Professor or university staff
Victoria, British Columbia, Canada

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I am a retired professor of chemistry at the University of Victoria, BC, Canada. My research areas are electrochemistry and surface science. I have been a user of Maple since about 1990.

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These are replies submitted by dharr

@Alfred_F A bit more, with a nice example at the end.

restart

z := tan(3*Pi/x)+4*sin(2*Pi/x)-sqrt(x)

tan(3*Pi/x)+4*sin(2*Pi/x)-x^(1/2)

Exact

simplify(eval(z, x = 11))

0

Change 4 to 4. (or 4.0 if you prefer

zf := tan(3*Pi/x)+4.*sin(2*Pi/x)-sqrt(x)

tan(3*Pi/x)+4.*sin(2*Pi/x)-x^(1/2)

Approximate answer

ansf := evalf(eval(zf, x = 11))

0.1e-8

If it is just roundoff error, fnormal will convert it to 0.  - notice the ".", but it is still not evidence of a true zero.

fnormal(ansf)

0.

The following is not 1, though it looks like it with default 10 digit calculations

q := -cos(Pi*cos(Pi*cos(ln(Pi+20)))); evalf(q)

-cos(Pi*cos(Pi*cos(ln(Pi+20))))

1.

Force 40 digit calculation accuracy

evalf[40](q)

.9999999999999999999999999999999999606784

NULL

Download floats.mw

@Ronan I usually copy the URL here so you can give it as additional information. Then go to the "more" tab on mapleprimes and choose submit software change request. Maple employees may notice stuff here, but I would submit the SQR anyway, just in case.

I get the same one-page result as you for both 2024 and 2025; both through exporting as .pdf or printing to the Adobe print driver. (Mac .pdf generation is different I believe.)

I agree with @nm that it's a bug. The following works and is shorter:

B:=<seq(A)>;

@JaneCherrytree Thanks. My point was to simplify the expression as much as possible before integrating, and in particular getting rid of square roots, but if it is correct then we have to live with the square root. What can we assume about the signs of the variables? Are they all positive?

You have

t1 := r*cos(phi);
t22 := (1 - s)*sqrt(1 - t1*t1) + s*t2;

So  sqrt(1 - t1*t1) = sqrt(1 -r^2*cos(phi)^2) seems wrong from a dimensional point of view since r^2*cos(phi)^2 has dimensions if r^2 and is subtracted from dimensionless 1. Is it supposed to be sqrt(r^2 -r^2*cos(phi)^2), which would simplify to r*sin(phi)

@salim-barzani

Quoting @mmcdara:

"This is for the simple reason that I can neither figure out what you're trying to achieve, nor be able to find a relationship between what you say in this reply and the code you provide."

"I hope you can find someone smarter than [us - me and @mmcdara ] - to help you.
Good luck"

@salim-barzani Please explain exactly in your worksheet sys.mw where eq1 comes from. I suggest you highlight the terms in red (in P?, E3?, somewhere else?) to show where they are. You presumably cut and pasted them from somewhere so you can highlight that place.

@salim-barzani So you don't want alpha_i and beta_i in the equation for U? What two terms are you talking about?

@salim-barzani So you want to generate these equations eq0..eq10? This can be done with the collect(...,'distributed'); coeffs(.., 'monomials'); and then if you put the monomials in a table you can pick out the monomials you want. This code you have seen before. I don't see what this has to do with factoring.

factor what? You mean all of eq0 to eq10? so map(factor, {eq0,...,eq10}); But this won't matter to solve.

@salim-barzani As you know, for consistency I always write ode's and equation to solve without the =0.

Maple itself doesn't have anything; at least ?fuzzy does not return anything. But the application center has four applications to do with fuzzy sets or fuzzy controllers; don't know if this includes fuzzy derivatives.

@salim-barzani Changed signs in ode to match trigh solution. The convert to exp shows Eq 3 can't be right, so I hacked it.

Download T1.mw

@salim-barzani I went through the code making a few changes but with the same result. I didn't check every equation with the paper, but since the final odetest succeeds, it seems everything is working. So I have no idea what you are actually asking, and am not going to spend more time unless you give a very specific question about a particular equation.

Dr.D-feedback2.mw

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