Someone asked on math.stackexchange.com about plotting x*y*z=1 and, while it's easy enough to handle it with implicitplot3d it raised the question of how to get nice constained axes in the case that the x- or y-range is much less than the z-range.

Here's what WolframAlpha gives. (Mathematica handles it straight an an plot of the explict z=1/(x*y), which is interesting although I'm more interested here in axes scaling than in discontinuous 3D plots)

Here is the result of a call to implicitplot3d with default scaling=unconstrained. The axes appear like in a cube, each of equal "length".

Here is the same plot, with scaling=constrained. This is not pretty, because the x- and y-range are much smalled than the z-range.

How can we control the axes scaling? Resizing the inlined plot window with the mouse just affects the window. The plot itself remains  rendered in a cube. Using right-click menus to rescale just makes all axes grow or shrink together.

One unattractive approach it to force a small z-view on a plot of a much larger z-range, for a piecewise or procedure that is undefined outisde a specific range.

plots:-implicitplot3d(proc(x,y,z)
                        if abs(z)>200 then undefined;
                        else x*y*z-1; end if;
                      end proc,
                      -1..1, -1..1, -200..200, view=[-1..1,-1..1,-400..400],
                      style=surfacecontour, grid=[30,30,30]);

Another approach is to scale the x and y variables, scale their ranges, and then force scaled tickmark values. Here is a rough procedure to automate such a thing. The basic idea is for it to accept the same kinds of arguments are implicitplot3d does, with two extra options for scaling the axis x-relative-to-z, and axis y-relative-to-z.

implplot3d:=proc( expr,
                  rng1::name=range(numeric),
                  rng2::name=range(numeric),
                  rng3::name=range(numeric),
                  {scalex::numeric:=1, scaley::numeric:=1} )
   local d1, d2, dz, n1, n2, r1, r2, rngs, scx, scy;
   uses plotfn=plots:-implicitplot3d;
   (n1,n2) := lhs(rng1), lhs(rng2);
   dz := rhs(rhs(rng3))-lhs(rhs(rng3));
   (scx,scy) := scalex*dz/(rhs(rhs(rng1))-lhs(rhs(rng1))),
                scaley*dz/(rhs(rhs(rng2))-lhs(rhs(rng2)));
   (r1,r2) := map(`*`,rhs(rng1),scx), map(`*`,rhs(rng2),scy);
   (d1,d2) := rhs(r1)-lhs(r1), rhs(r1)-lhs(r1);
   plotfn( subs([n1=n1/scx, n2=n2/scy], expr),
           n1=r1, n2=r2, rng3, _rest[],
           ':-axis[1]'=[':-tickmarks'=[seq(i=evalf[3](i/scx),i=r1,d1/4)]],
           ':-axis[2]'=[':-tickmarks'=[seq(i=evalf[3](i/scy),i=r2,d2/4)]],
           ':-scaling'=':-constrained');
end proc:

The above could be better. It could also detect user-supplied custom x- or y-tickmarks and then scale those instead of forming new ones.

Here is an example of using it,

implplot3d( x*y*z=1, x=-1..1, y=-1..1, z=-200..200, grid=[30,30,30],
            style=surfacecontour, shading=xy, orientation=[-60,60,0],
            scalex=1.618, scaley=1.618 );

Here is another example

implplot3d( x*y*z=1, x=-5..13, y=-11..5, z=-200..200, grid=[30,30,30],
            style=surfacecontour, orientation=[-50,55,0],
            scaley=0.5 );

Ideally I would like to see the GUI handle all this, with say (two or three) additional (scalar) axis scaling properties in a PLOT3D structure. Barring that, one might ask whether a post-processing routine could use plots:-transform (or friend) and also force the tickmarks. For that I believe that picking off the effective x-, y-, and z-ranges is needed. That's not too hard for the result of a single call to the plot3d command. Where it could get difficult is in handling the result of plots:-display when fed a mix of several spacecurves, 3D implicit plots, and surfaces.

Have I overlooked something much easier?

acer

Maplesoft regularly hosts live webinars on a variety of topics. Below you will find details on some upcoming webinars we think may be of interest to the MaplePrimes community.  For the complete list of upcoming webinars, visit our website.

Maplesoft Solutions for Math Education

This webinar will demonstrate how Maplesoft’s solutions for mathematics education help teachers bring complex problems to life, allow students to focus on concepts rather than the mechanics of solutions, and offer students the necessary practice to master the concepts being taught.

Key takeaways include:

• How to quickly and painlessly place incoming students in the correct math courses

• How you can use hundreds of intuitive Clickable Math tools to demonstrate and explore up to advanced-level problems and algorithms in the classroom

• How to automate your testing and assessment needs, specifically for math courses

• How to bring your STEM courses to life in an online environment

To join us for the live presentation, please click here to register.

Introduction to Maple T.A. Placement Test Suite 10

This webinar will provide an overview and demonstration of the latest release of the Maple T.A. MAA Placement Test Suite. A result of the ongoing partnership between the Mathematical Association of America (MAA) and Maplesoft, this product gives you the ability to provide the renowned MAA placement tests in an online testing environment. Learn how the Maple T.A. MAA Placement Test Suite can greatly simplify your placement process and explore the latest additions, including a streamlined interface and new tests to determine your students’ readiness for Precalculus and Algebra courses.

To join us for the live presentation, please click here to register.

There is also a recording available from another live webinar we did earlier this month: Introduction to Maple T.A. 10.

Aujourd’hui, je suis ravis d’annoncer la disponibilité d’une large banque de questions françaises supportant les enseignements du secondaire et de l’enseignement supérieur. Ce contenu didactique est disponible via le MapleTA Cloud, et également grâce au lien de téléchargement ci-dessous.

Lien de téléchargement de la banque de questions françaises

Ces questions sont librement et gratuitement accessibles, et vous pouvez les utiliser directement sur vos propres évaluations et exercices dans MapleTA, ou les éditer et modifier pour les adapter à vos besoins.

Le contenu de cette banque de questions françaises traite de sujets pour les classes et enseignements pré-bac, post-bac pour en majorité les matières scientifiques.

Les matières traitées par niveaux et domaines sont:

Lycées :

• Electricité
• Équations Différentielles
• Gravitation universelle
• Langues
• Maths I
• Maths II
• Physique
• Chimie
• Mécanique

Enseignement supérieur (Post-Bac) :

• Astrobiologie
• Introduction au Calcul pour la Biologie
• Chimie
• Déplacement d'onde
• Electricité & Magnétisme
• Maths pour l’économie
• Maths Post-Bac
• Mécanique Angulaire
• Mécanique des Fluides
• Mécanique linéaire
• Physique Post-Bac
• Electrocinétique
• Matériau
• Mécanique des Fluides
• Thermodynamique

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Introductory Calculus Maple T.A.. course module developed by Keele University.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

These questions are designed to accompany the first semester of an introductory honours calculus course. The course is intended primarily for students who need or expect to pursue further studies in mathematics, physics, chemistry, engineering and computer science. With over 250 question, topics include: basic material about functions, polynomials, logs and exponentials, the concept of the derivative, and lots of practise exercises for finding derivatives and integrals, and material about series.

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Introductory Calculus for Biological Sciences Maple T.A.. course module developed by the University of Guelph.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

The Introductory Calculus for Biological Sciences course module is designed to cover a single-semester introductory calculus course for biological sciences students at the first-year university level. The questions are designed to span the topics listed below, allowing for practice, homework or testing throughout the semester.

Topics include:

• Introduction to Functions
• Composite and Inverse Functions
• Trigonometric Functions
• Logarithms and Exponents
• Sequences and Finite Series
• Limits and Continuity
• Derivatives
• Curve Sketching
• Differentials
• Linear Approximation
• Taylor Polynomials
• Difference Equations
• Log-Log Graphs
• Anti-Differentiation
• Definite Integrals

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Erik Postma from Maplesoft has recently posted a Maple application going through some of the ways how to produce random numbers in Maple: http://www.maplesoft.com/applications/view.aspx?SID=153662&P=TC-4444

Doing a fair bit of work involving random numbers (i.e. simulations) myself, I was naturally drawn to it. The document is a nice extension of the relevant help pages, making practical use of some of the procs in RandomTools easier and clearer.

One particular issue I recently ran into, however, is not covered. I needed a random generator for a particular custom pdf (not one of the already recognized pdfs) that happens to be 3-dimensional. And I needed to do this >twice<, with the second generation using the result of the first one as a parameter. the problem is not unlike the last example in the help page for Statistics:-Sample.

Here is what I did:

The pdf looks graphically like this (and note that in this plot it is not normalized):

plot3d(Triangle63:-Trianglef(CrystalAngle,DeflectionAngle),\
       CrystalAngle=-0.8..0.2,DeflectionAngle=-0.6..0.6,projection=0.7);

The first set of random numbers is generated by setting CrystalAngle to a fixed number (-0.1 in this case), normalizing the pdf to the integral over DeflectionAngle and then generating the random numbers. Note that evaluation of the integral is relatively time-consuming (seconds).

trianglepdf:=(CrystalAngle,DeflectionAngle) ->\
             Triangle63:-Trianglef(CrystalAngle,DeflectionAngle)/\
             'evalf(Int(Triangle63:-Trianglef(CrystalAngle,Da),Da=-0.6..0.6,method = _d01akc))':
triangle0pdf:=(t) -> trianglepdf(-0.1,t):
Cr1:=Distribution(PDF=triangle0pdf);
Y:=RandomVariable(Cr1);

samples:=Sample(Y,[1..600],method=[envelope,range=-0.6..0.6]);

Histogram(samples,view=[-0.6..0.6,default],labels=["Deflection Angle  (µrad)","Counts/bin"]);

This looks as it should; and the random number generation is reasonably fast once the initial setup has been done (i.e. the time used scales only relatively weakly with the count of random numbers generated.

The issue now is the second stage, where for each new random number, the number generated above is a new input parameter for CrystalAngle. So I can no longer define the pdf once since the pdf is different for each number generated.

The pedestrian way to do this is like the following:

samples2:=Vector(1..numelems(samples),datatype=float):
CrystalOffset:=0.3;

for ii from 1 to numelems(samples) do
  triangleiipdf:=(t) -> (trianglepdf(samples[ii]-~CrystalOffset,t)); # subtract (VR peak -> 0)
  Crii:=Distribution(PDF=triangleiipdf);
  samples2[ii]:=evalf(Sample(RandomVariable(Crii),1,method=[envelope,range=-0.6..0.6])[1]+CrystalOffset);
end do:

This works, but only sort-of. First, it is very slow, since the whole sertup happens for each number generated (Sample()). Secondly, it tends to hang at a certain number of steps through the loop. The value of ii where it hangs is arbitrary and changes with the other parameters and CrystalOffset. It is however consistent for identical runs.

The last example in help for Statistics:-Sample would indicate that one needs to setup the pdf as a function of t as well as the parameter, call Distribution() only once and then assign the value to the parameter and call Sample() to get the random number(s) drawn from the pdf with the parameter being set to the wanted value. While this works in the example which uses a built-in pdf, I find that I cannot make it work with my pdf. Either the parameter gets ignored (i.e. stuck at the first value) or the thing runs just as slowly as my procedure above.

Ultimately I programmed my own random generator for an arbitrary pdf which, while not as efficient as Maple's built-in generator, does produce the expected set of random numbers for the 2nd path in a reasonable time. It is a simple-minded envelope-rejection method, that works fo reasonably well-behaved pdfs:

Rarbit:=proc(pdf,xmin,xmax,pdfmax)
local dx:=xmax-xmin;
local x1,x2;
x1:=RandomTools[MersenneTwister]:-GenerateFloat64()*dx+xmin; # pick location on x axis
x2:=RandomTools[MersenneTwister]:-GenerateFloat64()*pdfmax; # y axis, probability of returning x1

while (x2>evalf(pdf(x1))) do # if above pdf, reject
  x1:=RandomTools[MersenneTwister]:-GenerateFloat64()*dx+xmin; # new x-axis value
  x2:=RandomTools[MersenneTwister]:-GenerateFloat64()*pdfmax; # check value
end do; # eventually we'll succeed and return one.

x1;
end proc;

Using this routine I get my second and final set of randome:

for ii from 1 to numelems(samples) do
  newpdf:=(DefAng) -> Triangle63:-Trianglef(samples[ii]-CrystalOffset,DefAng);
  samples2[ii]:=Random:-Rarbit(newpdf,-0.6,0.6,28);
  DocumentTools:-SetProperty(ProgressBar,'value',ii,refresh);
end do:
                      CrystalOffset := 0.3
Histogram(samples2+~samples,view=[-0.6..0.6,default]);

 I would be interested in Erik's comment on this.

Mac Dude

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Introductory Mathematical Economics Maple T.A.. course module developed by the University of Guelph.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

The Introductory Mathematical Economics course module is designed to cover a single-semester course in mathematical economics for economics and commerce students at the second-year university level. The questions are designed to span the topics listed below, allowing for practice, homework or testing throughout the semester.

Topics include:

• Rules of Differentiation
• First Order Differential Equations
• Higher Order Derivatives
• Optimization in One Variable
• Second Order Conditions for Optimization
• Systems of Linear Equations
• Optimization with Direct Restrictions on Variables
• Over Determined and Under Determined Systems
• Matrix Representation of Systems
• Gauss Jordan
• Matrix Operations
• Types of Matrices
• Determinants and Inverses
• Partial Differentiation
• Second Order Partial Derivatives
• Multivariate Optimization
• Second Order Conditions for Multivariate Optimization
• Multivariate Optimization with Direct Restrictions of Variables
• Constrained Optimization and the Lagrangean Method
• Second Order Conditions for Constrained Optimization

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Introductory Electricity & Magnetism Maple T.A.. course module developed by the University of Guelph.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

The Introductory Electricity & Magnetism course module is designed to cover a single-semester course in electricity and magnetism for physical sciences students at the first-year university level. The questions are designed to span the topics listed below, allowing for practice, homework or testing throughout the semester. Using the Maple engine that is part of Maple TA, a custom grading engine has been developed to provide even more flexible grading of scalar and vector responses. This partial grading engine can be configured to, among other things, assign part marks for missing units, transposed or missing vector components or missing algebraic terms.

Topics include:

• Cross Products
• Coulomb’s Law
• Electric Fields
• Point Charge Distributions
• Continuous Charge Distributions (Integration)
• Electric Potential
• Electric Potential Energy
• Electromotive Force
• Resistance
• Capacitance
• Kirchhoff’s Laws
• Magnetic Fields
• Magnetic Fields Due to Current Carrying Wires
• Forces on Wires in Magnetic Fields
• Forces on Charges in Electric and/or Magnetic Fields
• EM Waves
• Two Source Interference
• Double Slit Interference
• Single Slit Diffraction
• Diffraction Gratings

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Statistics Maple T.A.. course module developed by the University of Guelph.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

The Statistics course module is designed to cover a single-semester course in statistics for science students at the second-year university level. The questions are designed to span the topics listed below, allowing for practice, homework or testing throughout the semester. The questions are mainly of an applied nature and do not delve very deeply into the underlying mathematical theory.

Topics:

• Introduction to Statistics
• Descriptive Statistics
• Basic Probability
• Discrete Random Variables
• Continuous Random Variables
• Sampling Distributions
• Inference for Means
• Inference for Proportions
• Inference for Variances
• Chi-square Tests for Count Data
• One-Way ANOVA
• Simple Linear Regression and Correlation

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Statistics Maple T.A.. course module developed by the University of Waterloo.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

The Statistics content is used in introductory statistics courses at the University of Waterloo, and has been used regularly over several years. The over 700 questions are clearly organized by topic, and provide extensive feedback to students.

Topics include:

• Basics
• Confidence Intervals
• Continuous Distribution
• Discrete Multivariate
• Discrete Probability
• Graphical Analysis
• Hypothesis Testing
• Numerical Analysis for Statistics
• Probability
• Sampling Distributions

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Several Maple T.A. users have developed comprehensive sets of question content and assignments to support full courses in Maple T.A. These questions are available through the Maple T.A. Cloud, and we have decided to also post the associated course modules on Maple Primes as an alternative way of accessing this content.

Below you will find a link to the Calculus 1 Maple T.A.. course module developed by the University of Guelph. This course material also forms part of Teaching Calculus with Maple: A Complete Kit, which provides lectures notes, Maple demonstrations, Maple T.A. assignments, and more for teaching both Calculus 1 and Calculus 2.

This testing content is freely distributed, and can be used in your own Maple T.A. tests either as-is, or with edits.

The Calculus 1 course module is designed to accompany the first semester of an introductory honours calculus course. The course is intended primarily for students who need or expect to pursue further studies in mathematics, physics, chemistry, engineering and computer science.

Topics include:

• trigonometry including the compound angle formulas
• inequalities and absolute values
• limits and continuity using rigorous definitions, the derivative and various applications (extreme, related rates, graph sketching)
• Rolle's Theorem and the Mean Value Theorem for derivatives
• the differential and anti-differentiation
• the definite integral with application to area problems
• the Fundamental Theorem of Calculus
• logarithmic and exponential functions
• the Mean Value Theorem for Integrals

The Calculus 2 course module is designed to accompany the second semester of an introductory honours calculus course.

Topics include:

• inverse trigonometric functions
• hyperbolic functions
• L'Hôpital's Rule
• techniques of integration
• parametric equations
• polar coordinates
• Taylor and MacLaurin series
• functions or two or more variables
• partial derivatives
• multiple integration

Jonny Zivku
Maplesoft Product Manager, Maple T.A.

Maplesoft regularly hosts live webinars on a variety of topics. Below you will find details on an upcoming webinar we think may be of interest to the MaplePrimes community.  For the complete list of upcoming webinars, visit our website.

Hollywood Math 2

In this second installment of the Hollywood Math webinar series, we will present some more examples of mathematics being used in Hollywood films and popular hit TV series. For instance, have you wondered how Ben Campbell solved his professor’s challenge so easily in the movie “21”? Or about the details of the Nash equilibrium that John Nash first developed in a “A Beautiful Mind”? We’ve got the answers! These relevant, and exciting examples can be used as material to engage your students with examples familiar to them, or you can just attend the webinar for its entertainment value.

Anyone with an interest in mathematics, especially high school and early college math educators, will be both entertained and informed by attending this webinar. At the end of the webinar you’ll be given an opportunity to download an application containing all of the examples that we demonstrate.

To join us for the live presentation, please click here to register.

If you missed the first webinar in this two part series, you can view the 'Hollywood Math' recording on our website.

We have issued an update to correct a problem a small number of Mac and 64-bit Linux users have experienced when doing certain types of floating point computations on very recent hardware (such as this report on MaplePrimes: http://www.mapleprimes.com/questions/201815-Problem-Loading-MKL-In-Maple-18). When the problem occurs, instead of giving the result, Maple issues a “lost kernel connection” error message and must be restarted.

While this issue does not occur on most computers, we recommend that all Maple 18 customers running on Mac or 64-bit Linux install this update to ensure they do not encounter this problem. This update can be safely applied to any Mac or 64-bit Linux computer. Windows and 32-bit Linux users do not need, and cannot install, this update.

To get this update, you can use Tools>Check for Updates from within Maple, or visit Maple 18.01a Downloads.

eithne

Maplesoft regularly hosts live webinars on a variety of topics. Below you will find details on some upcoming webinars we think may be of interest to the MaplePrimes community.  For the complete list of upcoming webinars, visit our website.

Bring Statistics Education to Life!

This exciting new webinar will demonstrate some of the ways that educators can take advantage of Maple’s symbolic and numeric approach for statistics education. Examples will include basic statistics theory including descriptive statistics such as measures of central tendency and spread, hypothesis testing, as well as discrete and continuous random variables.

Many examples presented in this webinar will be taken from the new Student Statistics package that was introduced in Maple 18. The Student Statistics was designed with classroom use in mind, and features detailed explanations and instructions, interactive demonstrations, and visualizations, all of which are great learning tools for teaching a course involving probability and statistics.

To join us for the live presentation, please click here to register.

Symbolic Computing for Engineering

As engineering applications become more complex, it is becoming increasingly difficult to satisfy the often-conflicting project constraints using traditional tools. As a result, we’ve found there is a growing interest within the engineering community for tools that make engineering calculations transparent and capture not just results but also the knowledge and analysis used throughout the engineering workflow. Engineering organizations are achieving this goal by making symbolic techniques an integral part of their tool set.

In this webinar, Laurent Bernardin will demonstrate how to enhance the early-stage design phase by making mathematical computations explicit and transparent, and then integrating the results into an existing tool chain.

To join us for the live presentation, please click here to register.

Maplesoft regularly hosts live webinars on a variety of topics. Below you will find details on some upcoming webinars we think may be of interest to the MaplePrimes community.  For the complete list of upcoming webinars, visit our website.

Bring Statistics Education to Life!

This exciting new webinar will demonstrate some of the ways that educators can take advantage of Maple’s symbolic and numeric approach for statistics education. Examples will include basic statistics theory including descriptive statistics such as measures of central tendency and spread, hypothesis testing, as well as discrete and continuous random variables.

Many examples presented in this webinar will be taken from the new Student Statistics package that was introduced in Maple 18. The Student Statistics was designed with classroom use in mind, and features detailed explanations and instructions, interactive demonstrations, and visualizations, all of which are great learning tools for teaching a course involving probability and statistics.

To join us for the live presentation, please click here to register.

Symbolic Computing for Engineering

As engineering applications become more complex, it is becoming increasingly difficult to satisfy the often-conflicting project constraints using traditional tools. As a result, we’ve found there is a growing interest within the engineering community for tools that make engineering calculations transparent and capture not just results but also the knowledge and analysis used throughout the engineering workflow. Engineering organizations are achieving this goal by making symbolic techniques an integral part of their tool set.

In this webinar, Laurent Bernardin will demonstrate how to enhance the early-stage design phase by making mathematical computations explicit and transparent, and then integrating the results into an existing tool chain.

To join us for the live presentation, please click here to register.