The Wonders of WolframAlpha

It is unworthy of excellent men to lose hours like slaves in the labor of calculation.
    Gottfried Wilhelm Leibniz

 

I have often told students that becoming good at math is a lot like becoming good at a sport or at playing an instrument – practice is extremely important. Hours and hours of practice.

However, there is a lot that can be learned from having computer software do math for you, especially if the math is algebra and calculus. The kind of programs that can do this are called Computer Algebra Systems (CAS), and they can actually do much more than just algebra. The most famous CAS is Mathematica from Wolfram Research, and another one called Maple is widely used. The mathematical manipulations these systems can do are remarkable, and the term artificial intelligence seems appropriate to describe them.

Unfortunately, both Mathematica and Maple cost hundreds of dollars, and most students could not justify that much expense. There are a few CAS programs that are free, and for a year or so, I experimented with one called Maxima. However, when Wolfram Research introduced WolframAlpha (W|A) in 2009, it seemed clear it was much superior. As many people know, W|A is web based and free, and it can do much more than just mathematics. My focus here is just on its math capability. W|A gives us access to a substantial subset of Mathematica, and those with an appreciation for math will often be amazed by what it can do.

Of special interest to the student, the page showing the problem solution often has a link called Show Steps. Clicking that will bring up a step-by-step explanation of how the solution was obtained.

An oddity of W|A is that there appears to be no formal documentation – just a series of sample commands that actually don’t cover nearly all of its capabilities. I have found a good many of the “hidden” commands by just trying things, or by looking at the Mathematica documentation for hints about things to try. The table below summarizes my exploration so far, and is more comprehensive than the W|A web site.

I welcome corrections and additions, and may post a revised version of the table later.

 

 

Algebra, Trigonometry

 

Equations

   

solve ax^3 + bx + c = 0 for x

 
   

solve sin(x)/x = .5

 
   

solve x^3-3x^2 =  x^6-2

 
 

Linear Algebra

   

{{2,0,5},{1,3,-6},{3,4,7}}

all properties of the 3×3 matrix

   

rotate 60 degrees

generate a rotation matrix

   

{1/4, -1/2, 1} cross {1/3, 1, -2/3}

Vector cross product

   

{1/4,-1/2,1} dot {1/3,1,-2/3}

Vector dot product

   

linearProgramming ({1, 1}, {{1, 2}},
{{3,-1}})

minimize x+y, subject to the constraint x+2y<=3.
For >=, make the last number 1. For =, make it 0

   

eliminate ({a x + y = 0, 2 x + (1 – a) y = 1}, y)

derive one equation with y eliminated

   

Simultaneous linear equations:

   

solve {{2,5},{1,3}},{x,y}={3,5}

Matrix form

   

or      solve 2x+5y=3, x+3y=5

Normal form

   

or
2x+5y=3, x+3y=5

without “solve”, it also plots the equations

 

Miscellaneous

   

partial fractions (x^2-4)/(x^4-x)

 
   

expand (2x-3y)^12

 
   

factor 6x^3 – 65x^2 + 13x + 84

 
   

complete the square 3x^2-4x+13

 
   

x^2 – 2x + 4 – y^2 + 5y + 1 = 0

Analyze and plot the conic

   

2.467401100272339654708622

recognizing numbers

   

(53+60i)/29

computes rectangular & polar form plus gaussian prime factors

   

((3-2i)(4+i)/(2-5i) +1+2i)e^(2i)

simplify complex expression

   

factor(4829490)

 

Graphing

   

plot  x^3-3x^2,  x^4-2

 
   

logplot e^(3x)

y axis is logarithmic

   

line through (2,3) and (6,4)

 
   

plot 3d (z=3x^2-4y^2)

3 dimensional plot

   

plot3D (sin(x + y^2), {x, -3, 3}, {y, -2, 2})

specify a range for x and y

   

polar plot r=theta, theta=0 to 8 pi

 
   

parametric plot (t-sin(t)),2(1-cos(t)) for  t=0 to 4*pi

 

Financial

In each case, entering the command results in a  form for specifying the input variables

   

compound interest

 
   

amortization calculator

 
   

future value

 
   

annuity

 

Statistics and Probability

   

{25, 35, 10, 17, 29, 14, 21, 31}

Descriptive statistics of the array

   

linear fit {{1.3, 2.2}, {2.1, 5.8}, {3.7, 10.2}, {4.2, 11.8}}

Linear regression. There’s also quadratic fit, cubit fit, log fit, and exponential fit

 

Distributions

In each case, enter the distribution name – a form will then request the input variables

   

binomialcdf, binomialpdf

 
   

chisquarecdf, chisquarepdf

 
   

normalcdf, normalpdf

 
   

poissoncdf, poissonpdf

 
 

Probability

   

combination 10,2

 
   

permutation 10,2

 
   

2 heads in 10 tosses

 
   

poker royal flush

 
   

3 dice

 
   

5 10 sided dice

 

Calculus

 

Differential calculus

   

derivative ( x^2 sin(x)^3+x^3sin(x)^2)

d/dx can be used in place of “derivative”

   

critical points x^4-5x^2+4x

 
   

d/dy (3ax^2y^3 + xy*sin(y)^2)

partial derivative

   

maximize -x^3+4x^2 on [-1, 5]

 
   

grad (3x^3y, xy^2,  xyz)

vector calculus (also div, curl operators)

 

Integral calculus

   

integral Log[x]

antiderivitative

   

integrate e^(-x^2) from 0 to +infinity

definite integrals

   

integrate e^(-x)sin(x) from  0 to pi

 
   

integrate e^(-x)  from 0 to infinity

improper integral

 

Limits and Series

   

limit sin[x]/x  x->0

 
   

taylor series of 1/ln(x)

 
   

sum n^4 from 1 to k

Get the formula for the sum

   

sum of [(ln(2)^n)+(1/(ln(4)^n))] from 0 to infinity

 
   

6,15,30,51,78,…

compute a possible formula for the series

 

Differential equations

   

solve y”(x)+x=0

 
   

solve y”(x) – y = 3x^2, y’(0)=1, y(0)=10

 

Functions

   

table [sin(x)/x^2,{x,1,pi,.2}]

Table of function values from 1 to pi, in increments of 0.2

   

j1() from -10 to 10

Plot Bessel function of first kind

   

zeta(.5+2i)

Evaluate function at a point

   

log (e^3)

Natural logarithm

   

log (12,144)

Logarithm to any base

   

laplaceTransform (e^(2x) sin(x))

 
   

inverseLaplace (1/(s^2+5s-16))

 
   

fourierTransform (e^(2x) sin(x))

 
   

19!

factorial

Physics

   

.007 joules in ergs

Unit conversions

   

projectile 23 degrees 42 m/sec

 
   

kinetic energy 47 kg 125 miles per hour

 
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2 Responses to “The Wonders of WolframAlpha”

  1. Carol Cronin Says:

    Dear Larry,

    I did want to mention that the price of Mathematica for Students is $139.95 and many students may access it for much less or even for free, if their school has a site license agreement.

    I’m glad you mentioned the documentation. We have a Wolfram|Alpha community site where users exchange ideas and suggestions, and we’d be thrilled to have you join.

    http://community.wolframalpha.com/

    Kindest regards,
    Carol

  2. Stephen Hutter Says:

    Wow. What a great reference. Thanks for writing this up! Am also enjoying your articles on Euler and primes.

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