## 688 Reputation

17 years, 52 days

## empty symbol...

Nice little trick to force maple to give a common denom by the way.

?empty symbol,  I'll check it out.  Thanks

## c'est la vie...

Okay, yes that works.

Haven't come across how to use an empty function (` `) yet and I haven't used the @ symbol.  Still have lots to learn.  Can't find any help on how to use the empty function but thanks for the reply.

## Need a little help...

Thanks, I appreciate your help.  That did the trick.

I didn't know what  set_EnvAllSolutions to true meant and I couldn't look it up.  Also wasn't sure what variable to assume to what.

I see, it looks like you've done it both ways, with an expression and then with a function.  That clears things up a little.

## Thanks...

Okay, thanks that does clear it up for me.

Maybe in a newer version of maple a function could be added to find the global maximum in a range.

## Thanks but it still gives the wrong answ...

I may not have typed in my funtion description properly but yes thanks for cleaning it up.  However even your worksheet does not give the maximum V for the function.

The maximum velocity DOES NOT occur at TMAX = 4.8687713762127175832    Maple should return T=4.24...

Maple should give me TMAX somewhere around 4.2 for positive.  At least.  I think it has something to do with it's floating point solve.  Maple missed the mark.

Now if I use VMAX:=Maximize(V,t=4..4.5); only then do I get the maximum velocity :  VMAX:=[23.968855..., [t = 4.2414933...etc..

Why is that?  Shouldn't if I choose t=4..6 return the same answer as if I choose t=4..4.5 ?  They both should return the same maximum if the maximum exists in both ranges.  Must be a problem with the way maple does it's internal calculations.

## .75 is exact...

Last time I remember 4 went into 3 exactly 0.75 times.  I don't see why maple should tack the zeros on.

If only zeros were left after the last number then they should be truncated and ignored ie float unless specifically forced to have 10 digits of precision as it appears maple currently does.

Can maple float the number in the sort of way I am asking?

## So if I evalf(3/4) maple...

So if I evalf(3/4) maple should give me .75 as the answer?  and not .75000000000

If you type 3/4. do you get the extra 0's?

Basically I'm not sure if I've changed, or one of the packages has changed, something in Maple or not.  I would like to know if this occurs as a default.  I'll have to try evelf(3/4) later this evening when I have a chance to see what happens.

But Isn't 3/4. exactly 0.75 anyway and so maple should no not have to add the zeros?

I did use Digits and I know it is defaulted at 10 places and if I use Digits :=20 it will give me 20 digits.  If 3/4 was allowed to float shouldn't it just stop at 0.75 since it's an exact value?

So what I want to know is, have I changed something to alter the original settings in maple?  or this is the normal way Maple works?

## thanks...

Okay yes it's working okay now.

I think the confusion revolves around using the double forward slashes as the directory path instead of the normal single backslash that the directory is usually displayed as.

## thanks...

You're right!  Thanks.  Must have been a misprint in the book, where the second equation should have equated to 1 and not 0.  I only checked the answer against the first equation.

## Bug...

So 5/(2*a) works fine but as soon as you add a variable in the numerator the number gets separated into a separate fraction.

Classic works fine with simple stuff like this.  I wonder how this one slipped by in the standard maple.

Has this issue been reported?

## Here's the problem...

Take any expression, let's say  Eq1 := (c-3b)/a   then in the next line divide it by two %/2  you get 1/2 * (c-3b)/a  and not (c-3b)/(2a) as I would think one would simplify to.

So I think it's a problem that lies with a lot of other expressions as well.  I'm sure you could take any expression with some variable in the denominator and get the 1/2 * part.  In fact even b/a then divide by 2 you get the 1/2.  Even if you type b/(2a) you get 1/2*(b/2).  That's odd isn't it?

This issue isn't just confined to my example.  Maple, can you fix this?

## sigh...

Alas, it will not work in the standard worksheet or document with or without anti-font aliasing or having the default input set to Maple input.  Maybe if someone knows a way it will work in the standard worksheet (or document) they could post their findings here.

Fonts are typed as normal and I'm not sure that scaled would make a difference in this case.  And just how do you propose to get into 1-D mode in the standard worksheet when that option just isn't there?

Classic worksheet does work for me, but I prefer the standard worksheet and I'd like to know it's working properly and organizing the equations correctly.  In this case it doesn't quite seem to be working properly, maybe they will have a fix for it?  Perhaps the Classic worksheet version is the one they were using in the book?  As it never said what maple version or type of mode they were using, although the book was just meant for getting basic ideas across.

So, did anyone get maple in the standard version to solve like the classic version?  Is it really a font issue?

## Yes...

Okay, sorry.  Found an answer in a related post earlier on about plotting 3 dimensional matricies.

I don't think we can view them the same way as a 2-d matrix.  Maybe future versions could view them by rotation or even the same 2-d layout with a depth level or something.

## Sure - I'll give it a shot...

Okay it's been a while since I was here and worked on that command.  It took me a while to figure it out but basically, internally it lays everything out in a matrix and calculates the mod and matches the number to one which then cross references it with the value that gave it one and displays that value.  That's it, quickly in a nutshell.

If you take an hour of your time and look up each command in the help file (match, index, mod, row, indirect etc... ) and disect the formula you should eventually be able to figure out how it works.  It's definitely confusing at first but quite ingenious, I say that because it took me quite some time to actually figure it out.  Right now as I write I have somewhat forgotten exactly how it works but with a little time it wouldn't take long.  It was basically for a cryptography project I was working on which I have since forgotten about.  Anyways, by the date of the post I'm sure you've already figured it out.

## Well, somewhat...

It does somewhat. In my example Mod(7,23) =MATCH(1,INDEX(MOD(ROW(INDIRECT("1:"&A1))*B1,A1),0 ),0) calculates the modulus of all the numbers from (1 to 23) multiplied by 7 and returns the values. It then matches the remainder that has a value of one and returns the value that gave that remainder. Very ingenious indeed.
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