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Quadratic problem - formatting issue

Posted on 2008-03-27 21:05 By Chris Roung (Maple Rating 2 119)
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A book had shown me using maple that if I solve({x2+bx+c=0},{x});

I would get x = (-b + sqrt(b^2-4ac)) / 2  and x = -b - ...    a normal way, the way everyone simplifies it as. 

 

However maple prints out  x = (-1/2) * (b-sqrt(b^2-4ac))/a  and the other x= ....

It is correct, however the formatting is ugly.  Why doesn't it show the same expression in the book which shows maple displaying it properly? 

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gkokovidis's picture

Quadratic

Comment on 2008-03-27 21:53 from gkokovidis (Maple Rating 4 770)

>restart:

>solve(a*x^2 + b*x + c, x);

This yields the familiar formula from the text.

You can also save your worksheet and upload it so that we can have a look.  I am using the Classic Interface.  Maybe this has to do with the Standard Interface and 2-D math. 


Regards,
Georgios Kokovidis
Dräger Medical

quadratic formula typesetting

Comment on 2008-03-27 22:15 from Alex Smith (Maple Rating 3 324)

Interesting...in Classic 11

solve(a*x^2 + b*x + c, x);

 returns the familiar form of a quotient. So the denominator is 2a.

In Standard 11 worksheet, we get a product. So we get 1/2*stuff.

 

JacquesC's picture

File bugs!

Comment on 2008-03-27 22:31 from JacquesC (Maple Rating 4 1728)

I am not sure if the Maplesoft developers really know how much the Standard prettyprinter is a very serious regression from Classic.  This is but one example.  There are all sorts of issues with baselines that are too high or too low, exponents that are too high, too low, too far left or right [same with subscripts], weird placement of minus signs, extra parenthesis when they are not needed, missing parentheses when they are, etc.  Also the fonts they use are fuzzier - I don't know where that comes from.  I know this was an issue with WebEQ as well; that turned out to be because for some (stupid!) reason a weird (and completely unecessary) scaling factor was applied to all glyphs, thus making them fuzzy.  If the fonts are used 'scaled' instead of at their natural sizes, that might be the cause.  But the worst is probably the line-breaking.  VERY often I have seen a break in an expression that looks like expr^(1/3) + expr2^(1/3) where the break is to put just the ^(1/3) [typeset as a superscript] on its own on the next line!  Sometimes, I have even see weird things like just an open ( on one line at the end, and the rest of the expression on the next.  Just incredible stuff.

But as I use Classic in part because I can't stand how awful the math now looks, and in part because I mostly use Maple to get some work done and Classic allows me to do that much more efficiently.  Standard, even in 1D worksheet mode, is not nearly as responsive as Classic.  Plus Standard has  lost the % labelling on large expressions.

acer's picture

sigh

Comment on 2008-03-27 23:21 from acer (Maple Rating 4 1723)

It's been four releases (5 years) of the Standard GUI now, that many of those things have been missing.

I miss all the easy colourizing control that the X11_defaults/Maple resource configuration file gives for the Classic UI. (Blaming such loss, in Standard, on Java is fun but doesn't help any.)

And the fuzzy fonts have been a big disappointment. Is font anti-aliasing off by default? (Turned on, it used to sometimes cause leading minus signs to display erroneously as merged with fraction-bars.)

Is hardware acceleration of plots still turned off by default, and how does one tell in 11.02? (When did that first appear? MapleV R5.1 , or am I thinking of something else?)

I prefer Maple's TTY interface. It's the definition of rock solid.

acer

gkokovidis's picture

quadratic formula typesetting

Comment on 2008-03-27 22:32 from gkokovidis (Maple Rating 4 770)

When I see these types of problems and execute them using the Classic Interface, and I get the correct response, I assume the problem has to do with the Standard Interface.  Even when I do use the Standard Interface, I have it set up so that the default input method is 'Maple Input" and not 2-D math.

 

Regards,
Georgios Kokovidis
Dräger Medical

sigh

Comment on 2008-03-28 20:58 from Chris Roung (Maple Rating 2 119)

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?

acer's picture

not a font issue

Comment on 2008-03-28 23:13 from acer (Maple Rating 4 1723)

I don't believe that anyone intended to convey that this might be a font issue. It's more that some of us miss more about the Classic interface than just its superior typesetting and 2D output layout capabilities.

At one point I had hoped that setting the prettyprint level might resolve it, if only for this one example. That is,

interface(prettyprint=1):

But I now believe that this is not adequate either.

acer

acer's picture

one kludge

Comment on 2008-03-28 23:43 from acer (Maple Rating 4 1723)

Here's a kludge, for just this one example.

It works by substituting the name `2` for the number 2 in the two fractions 1/2 and -1/2. (That's the non-technical explanation. Experts may nit-pick...) The 2D fraction layout works better for pure names in the denominator. Conversion back can be accomplished using expand().

> restart:

> sol:=solve({x^2+b*x+c},{x});

     /                        (1/2)\    /                        (1/2)\ 
     |      1     1 / 2      \     |    |      1     1 / 2      \     | 
    < x = - - b + - \b  - 4 c/      >, < x = - - b - - \b  - 4 c/      >
     |      2     2                |    |      2     2                | 
     \                             /    \                             / 


> op(simplify(subs(-1/2=-1/`2`,1/2=1/`2`,[sol])));

           /                    /1\\    /                    /1\\ 
           |                    |-||    |                    |-|| 
           |                    \2/|    |                    \2/| 
          <           / 2      \    >  <           / 2      \    >
           |      b - \b  - 4 c/   |    |      b + \b  - 4 c/   | 
           |x = - -----------------| ,  |x = - -----------------| 
           \              2        /    \              2        / 


> expand(%);

                          /                    /1\\ 
                          |                    |-|| 
                          |                    \2/| 
                         <           / 2      \    >
                          |      b   \b  - 4 c/   | 
                          |x = - - + -------------| 
                          \      2         2      /

Notice that it also makes the sqrt display as power-1/2, which you may not enjoy. That too could be side-stepped, but the code might then look too involved.

acer

Here's the problem

Comment on 2008-03-29 09:47 from Chris Roung (Maple Rating 2 119)

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?

Bug

Comment on 2008-03-29 10:49 from Chris Roung (Maple Rating 2 119)

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? 

JacquesC's picture

Always better to report it anyways

Comment on 2008-03-29 11:52 from JacquesC (Maple Rating 4 1728)

It is much simpler for Maplesoft to deal with duplicate reports than to expect them to fix bugs that have never been reported!  File away.  If a bug gets reported many many times, then that means that a lot of people have encountered it, so it is even more important that it get fixed.  [# of times reported used to be tracked in the database, although I am not sure if it is anymore]

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