We are trying to create an animation of arrows, where we calculate the vertices of the arrow in a procedure.  We are receiving the error:

Error, (in peak_slow) cannot determine if this expression is true or false: t < -.4506938557
 

where the animate command is trying to evaluate our procedure instead of calculating the value.  The procedure is

I'm one of several technical writers at Maplesoft.  It's our job to craft the text in our brochures and user stories, and on our web site.  We all have differing styles, but we share a common goal; we want to write in a manner that’s technically compelling but simple to understand.

After recently exploring Maple’s string manipulation tools, I was surprised to find a command that measures the readability of a sample of English text.  It seems that as well as making you a better mathematician, Maple will poke and prod you into being a better writer.

StringTools[Readability] returns a measure of readability called the SMOG index (but, when asked, will also give the Flesch Reading Ease, Flesch-Kincaid Grade Level Formula, Automated Readability and the Coleman-Law indices).

These measures do not gauge the quality of the writing, its grammatical correctness, or account for specialized discipline-specific vocabulary. They simply use guidelines determined from in-the-field studies (largely conducted in the US) to quantify the degree of education or effort it takes to understand a sample of text.  Additionally, the calibration of the results against the required reading effort is only meaningful for readers whose native language is English, and whose schooling resembles that of the US system.

The SMOG index wins an award for the most amusing acronym of the month: Simple Measure of Gobbledegook. It's calculated with the following empirical formula.

 It returns the years of education (that is, the US grade level) required to completely understand a sample of text.  Typically, Newsweek has a SMOG index of 10 to 11, the New York Times 13 to 15, and the Harvard Law Review 17 to 18.

I was recently asked to describe MapleSim in less than 70 words; this was the result:

MapleSim is a tool for multi-domain physical modeling and control systems development.  Physical components and signal-flow blocks can be connected to create models that map onto the real system. It features an integrated environment in which the system equations can be automatically generated and analyzed, and new physical components created. It contains tools for optimized code generation, controls analysis and design documentation.

This has a SMOG index of 15.5, which implies the reader needs a university education for complete comprehension.  Since that’s the target audience, I guess I’m in the right ballpark.

As I write this post, I know I’m guilty of making many readability errors.  Are my fellow Maplesoft bloggers as guilty?

To answer this question, I used Maple to calculate the SMOG index for all the blog posts on Maplesoft.com (but first stripping out code snippets or URLs that would distort the score).  The top 10 and the bottom 10 scores are given below.

Well...it appears that I’ve written some of the most readable posts and the single least readable post.  The two least readable blog posts are those that explore abstract, high-level ideas (and hence demand more sophisticated writing), while the most readable blog posts are essentially opinion pieces.

Other than that, the only conclusion we can make is that good writers tend to write to the level of comprehension of the intended audience and the material; they don’t unnecessarily dumb down the sophistication of their writing to the lowest common denominator, or write to a level that’s beyond the scope of the material.

I’ve attached a Maple worksheet that helps you explore the readability of text using all of the measures in StringTools[Readability].  You may want to use it to write a more readable blog post than this one.

I gave Maple the command

> ?fft 

to see how to do the fast fourier transform in Maple, and I what I got was a page that told me to use the commands:

> with(Matlab)

>v:=<1,2,3,2,3,4>

>Matlab[fft](v)

Why is maple using matlab ??

Can the size (width, length) of a 2D plot be specified programmatically? In particular, when a document is re-executed, I would like the graph outputs of plot(...) to be automatically sized to pre-defined values, for example to fit a full page. Right now, I am having to re-size each of my plots manually. For creating a report with many graphs, this is annoying to do and leads to plots that are not always exactly the same size.

I am thinking of the equivalent of ...

> plot(x^2,x=0..2,[width=6in,height=8in])

or ...

Does any way exist to bind keystrokes to menu commands? In particular, I frequently use sub and superscripts in text (I'm doing lots of chemical formula). That I have to search to a sub-sub-menu level to make these changes for individual characters is constantly annoying. Binding specific keystrokes (ctrl-underscore and ctrl-plus for example) to change character styles would be most useful in this case.

If this is not possible to do, consider it a feature request!

--

JJW

Download int_vs_sum_for_mr.mw

Looking at the attached worksheet,

it appears that the absolute value, minus 1/2, of the integral of (-1)^x*x^(1/x) from 1 to infinity would equal the partial sum of (-1)^x*x^(1/x) from 1 to where the upper summation is even and growing without bound [0]. Is anyone interested in improving or disproving this conjecture? 

This is a follow-up to an earlier post about CovarianceMatrix.

There are several ways in which Statistics:-CorrelationMatrix can be improved.

CorrelationMatrix shares some inefficiencies with CovarianceMatrix, by computing correlations between the n columns, pairwise. But in doing so it also computes...

Hello eveyone,

I'm experiencing a frustrating problem, trying to get maple to solve a system of differential equations. I have defined my system as:

f:=1-2*(n+1)*b*xi^2*nu(xi):

sys:={diff(nu(xi),xi)=(theta(xi)^n - 3*nu(xi)), diff(psi(xi),xi)=(n+1)*b*xi*theta(xi)^n*(1+b*theta(xi))/f, diff(theta(xi),xi)=-(nu(xi)+b*theta(xi)^(n+1))*xi*(1+b*theta(xi))/f, theta(xi=0)=1, nu(xi=0)=1/3};
 

The only part worth concentrating on is the part I've made bold. I then can solve the system near xi=0 witha  series solution:

Hi there,

I have a 2-D ODE system. Objective: plot the nullclines and phase diagram around the equilibrium point. Problem: one of the ODEs has an integral and a call to DEtools[dfieldplot] returns:

Error, (in DEtools/dfieldplot) extra unknowns found

I have created a minimal example below.

Maple's package DiscreteTransforms is a bit skinny, I miss various ones like discrete cosine transforms (at least the most 4 types), sine transform, Hartley transform, z-transform and may be the fractional Fourier transform or symmetric FTs (not sure for the whole herd).

It should be available, if Maple wants to be a numerical tool for technical users (all kinds of engineering I would say): it would not make sense for them to use other libraries, compile and finally combine with Maple, because it does not have it.

It seems like everywhere you turn lately, people are talking about how to be kinder to the planet. One example is just how much interest was generated when GM unveiled its plans for the Chevy Volt last year. As I write this, 46,527 people are on the waiting list for the upcoming electric car, which is scheduled to be released in late 2010 as a 2011 model. At my house, we wash our clothes in cold water; use a programmable thermostat; turn off the lights when we’re not in a room; recycle and compost our waste; use a low flush toilet, energy efficient appliances, and an electric lawnmower; and of course, snuggle our two dogs for warmth!   

Yesterday was one of those remarkable days when everything seems just about right. The highlight was an email message I received from a Prof. Fang from Ryerson University notifying us that we had been both nominated and awarded the Omond Solandt Award by the Canadian Operational Research Society for ongoing and outstanding contribution to the field of Operations Research (OR). No, it’s not a Nobel Prize or an Oscar, but whenever a group of smart people publically recognize our work, the honor and pride are genuine.