Advanced Search

aroche

Dr. Austin Roche

305 Reputation

7 Badges

11 years, 296 days
Maplesoft
Waterloo, Ontario, Canada
Contact Dr. Austin Roche
I am a Software Architect in the Math Group, working mostly on the Maple library. I have been working at Maplesoft since 2007, in various areas including differential equations, integration, mathematical functions, simplification, root finding, and logic. I completed a Master's degree from McGill University with a thesis in Differential Geometry, and a PhD from Simon Fraser University with a thesis on Differential Equations.

MaplePrimes Activity


These are Posts that have been published by aroche

Introducing VerifyTools...

aroche 305 Maple
verify verification typetools
August 21 2024
6 2

VerifyTools is a package that has been available in Maple for roughly 24 years, but until now it has never been documented, as it was originally intended for internal use only. Documentation for it will be included in the next release of Maple. Here is a preview:

VerifyTools is similar to the TypeTools package. A type is essentially a predicate that a single expression can either satisfy or not. Analogously, a verification is a predicate that applies to a pair of expressions, comparing them. Just as types can be combined to produce compound types, verifications can also be combined to produce compund verifications. New types can be created, retrieved, queried, or deleted using the commands AddType, GetType (or GetTypes), Exists, and RemoveType, respectively. Similarly in the VerifyTools package we can create, retrieve, query or delete verifications using AddVerification, GetVerification (or GetVerifications), Exists, and RemoveVerification.

The package command VerifyTools:-Verify is also available as the top-level Maple command verify which should already be familiar to expert Maple users. Similarly, the command VerifyTools:-IsVerification is also available as a type, that is,

VerifyTools:-IsVerification(ver);

will return the same as

type(ver, 'verification');

The following examples show what can be done with these commands. Note that in each example where the Verify command is used, it is equivalent to the top-level Maple command verify. (Also note that VerifyTools commands shown below will be slightly different compared to the Maple2024 version):

> 

with(VerifyTools):

Suppose we want to create a verification which will checks that the length of a result has not increased compared to the expected result. We can do this using the AddVerification command:

> 

AddVerification(length_not_increased, (a, b) -> evalb(length(a) <= length(b)));

First, we can check the existence of our new verification and get its value:

> 

Exists(length_not_increased);

true

> 

GetVerification(length_not_increased);

proc (a, b) options operator, arrow; evalb(length(a) <= length(b)) end proc

For named verifications, IsVerification is equivalent to Exists (since names are only recognized as verifications if an entry exists for them in the verification database):

> 

IsVerification(length_not_increased);

true

On the other hand, a nontrivial structured verification can be checked with IsVerification,

> 

IsVerification(boolean = length_not_increased);

true

whereas Exists only accepts names:

> 

Exists(boolean = length_not_increased);

Error, invalid input: VerifyTools:-Exists expects its 1st argument, x, to be of type symbol, but received boolean = length_not_increased

The preceding command using Exists is also equivalent to the following type call:

> 

type(boolean = length_not_increased, verification);

true

Now, let's use the new verification:

> 

Verify(x + 1/x, (x^2 + 1)/x, length_not_increased);

true

> 

Verify((x^2 + 1)/x, x + 1/x, length_not_increased);

false

Finally, let's remove the verification:

> 

RemoveVerification(length_not_increased);
> 

Exists(length_not_increased);

false

> 

GetVerification(length_not_increased);

Error, (in VerifyTools:-GetVerification) length_not_increased is not a recognized verification

GetVerifications returns the list of all verifications known to the system:

> 

GetVerifications();

[Array, FAIL, FrobeniusGroupId, Global, Matrix, MultiSet, PermGroup, RootOf, SmallGroupId, Vector, address, after, approx, array, as_list, as_multiset, as_set, attributes, boolean, box, cbox, curve, curves, dataframe, dataseries, default, default, dummyvariable, equal, evala, evalc, expand, false, float, function, function_bounds, function_curve, function_shells, greater_equal, greater_than, in_convex_polygon, indef_int, interval, less_equal, less_than, list, listlist, matrix, member, multiset, neighborhood, neighbourhood, normal, permute_elements, plot, plot3d, plot_distance, plotthing_compile_result, polynom, procedure, ptbox, range, rational, record, relation, reverse, rifset, rifsimp, rtable, set, sign, simplify, sublist, `subset`, subtype, superlist, superset, supertype, symbol, table, table_indices, testeq, text, true, truefalse, type, undefined, units, vector, verifyfunc, wildcard, xmltree, xvm]

Download VerificationTools_blogpost.mw

Austin Roche
Software Architect
Mathematical Software
Maplesoft

New and improved integration results in ...

aroche 305 Maple 2016
integration
March 11 2016
12 16

The attached worksheet shows a small selection of new and improved results in integration for Maple 2016. Note that integration is a vast topic, so there will always be more improvements that can be made, but be sure that we are working on them.

Maple2016_Integration.mw

A selection of new and improved integration results for Maple 2016

New answers in Maple 2016
 

 

Indefinite integrals:

 

> 

int(sqrt(1+sqrt(z-1)), z);

(4/5)*(1+(z-1)^(1/2))^(5/2)-(4/3)*(1+(z-1)^(1/2))^(3/2)

 (1.1)
> 

int(arctan((-1+sec(x))^(1/2))*sin(x), x);

-arctan((-(1/sec(x)-1)*sec(x))^(1/2))/sec(x)+(1/2)*(-1+sec(x))^(1/2)/sec(x)+(1/2)*arctan((-1+sec(x))^(1/2))

 (1.2)
> 

int(((1+exp(I*x))^2+(1+exp(-I*x))^2)/(1-2*c*cos(x)+c^2), x);

-x-2*x/c-x/c^2+I*exp(I*x)/c-I*exp(-I*x)/c-I*c*ln(exp(I*x)-1/c)/(c-1)-I*ln(exp(I*x)-1/c)/(c-1)-I*ln(exp(I*x)-1/c)/(c*(c-1))-I*ln(exp(I*x)-1/c)/(c^2*(c-1))+I*c*ln(-c+exp(I*x))/(c-1)+I*ln(-c+exp(I*x))/(c-1)+I*ln(-c+exp(I*x))/(c*(c-1))+I*ln(-c+exp(I*x))/(c^2*(c-1))

 (1.3)
> 

int(x^4/arccos(x)^(3/2),x);

(1/4)*(-x^2+1)^(1/2)/arccos(x)^(1/2)-(1/4)*2^(1/2)*Pi^(1/2)*FresnelC(2^(1/2)*arccos(x)^(1/2)/Pi^(1/2))+(3/8)*sin(3*arccos(x))/arccos(x)^(1/2)-(3/8)*2^(1/2)*Pi^(1/2)*3^(1/2)*FresnelC(2^(1/2)*3^(1/2)*arccos(x)^(1/2)/Pi^(1/2))+(1/8)*sin(5*arccos(x))/arccos(x)^(1/2)-(1/8)*2^(1/2)*Pi^(1/2)*5^(1/2)*FresnelC(2^(1/2)*5^(1/2)*arccos(x)^(1/2)/Pi^(1/2))

 (1.4)

 

Definite integrals:

> 

int(arcsin(sin(z)), z=0..1);

1/2

 (1.5)
> 

int(sqrt(1 - sqrt(1+z)), z=0..1);

((4/5)*I)*(2^(1/2)-1)^(3/2)*2^(1/2)+((8/15)*I)*(2^(1/2)-1)^(3/2)

 (1.6)
> 

int(z/(exp(2*z)+4*exp(z)+10),z = 0 .. infinity);

(1/20)*dilog((I*6^(1/2)-3)/(-2+I*6^(1/2)))-((1/60)*I)*6^(1/2)*dilog((I*6^(1/2)-3)/(-2+I*6^(1/2)))+(1/20)*dilog((I*6^(1/2)+3)/(2+I*6^(1/2)))+((1/60)*I)*6^(1/2)*dilog((I*6^(1/2)+3)/(2+I*6^(1/2)))+((1/120)*I)*6^(1/2)*ln(2+I*6^(1/2))^2-((1/120)*I)*6^(1/2)*ln(2-I*6^(1/2))^2+(1/40)*ln(2+I*6^(1/2))^2+(1/40)*ln(2-I*6^(1/2))^2+(1/60)*Pi^2

 (1.7)
> 

simplify(int(sinh(a*abs(x-y)), y=0..c, 'method'='FTOC'));

(1/2)*(piecewise(x < 0, 0, 0 <= x, 2*exp(-a*x))+piecewise(x < 0, 0, 0 <= x, -4)+2*piecewise(c <= x, -cosh(a*(-x+c))/a, x < c, (cosh(a*(-x+c))-2)/a)*a-exp(-a*x)+piecewise(x < 0, 0, 0 <= x, 2*exp(a*x))+4-exp(a*x))/a

 (1.8)
> 

int(ln(x+y)/(x^2+y), [x=0..infinity, y=0..infinity]);

infinity

 (1.9)


Definite integrals with assumptions on the parameters:

> 

int(x^(-ln(x)),x=0..b) assuming b > 0;

(1/2)*erf(ln(b)-1/2)*Pi^(1/2)*exp(1/4)+(1/2)*Pi^(1/2)*exp(1/4)

 (1.10)
> 

int(exp(-z)*exp(-I*n*z)*cos(n*z),z = -infinity .. infinity) assuming n::integer;

undefined

 (1.11)


Integral of symbolic integer powers of sin(x) or cos(x):

> 

int(sin(x)^n,x) assuming n::integer;

` piecewise`(0 < n, -(Sum((Product(1+1/(n-2*j), j = 1 .. i))*sin(x)^(n-2*i-1), i = 0 .. ceil((1/2)*n)-1))*cos(x)/n+(Product(1-1/(n-2*j), j = 0 .. ceil((1/2)*n)-1))*x, n < 0, (Sum((Product(1-1/(n+2*j+1), j = 0 .. i))*sin(x)^(n+2*i+1), i = 0 .. -ceil((1/2)*n)-1))*cos(x)/n+(Product(1+1/(n+2*j-1), j = 1 .. -ceil((1/2)*n)))*ln(csc(x)-cot(x)), x)

 (1.12)
> 

int(cos(x)^n,x) assuming n::negint;

-(Sum((Product(1-1/(n+2*j+1), j = 0 .. i))*cos(x)^(n+2*i+1), i = 0 .. -ceil((1/2)*n)-1))*sin(x)/n+(Product(1+1/(n+2*j-1), j = 1 .. -ceil((1/2)*n)))*ln(sec(x)+tan(x))

 (1.13)
> 

int(cos(x)^n,x) assuming n::posint;

(Sum((Product(1+1/(n-2*j), j = 1 .. i))*cos(x)^(n-2*i-1), i = 0 .. ceil((1/2)*n)-1))*sin(x)/n+(Product(1-1/(n-2*j), j = 0 .. ceil((1/2)*n)-1))*x

 (1.14)

Improved answers in Maple 2016
 
> 

int(sqrt(1+sqrt(x)), x);

(4/5)*(1+x^(1/2))^(5/2)-(4/3)*(1+x^(1/2))^(3/2)

 (2.1)
> 

int(sqrt(1+sqrt(1+z)), z= 0..1);

-(8/15)*2^(1/2)-(8/15)*(1+2^(1/2))^(3/2)+(4/5)*(1+2^(1/2))^(3/2)*2^(1/2)

 (2.2)
> 

int(signum(z^k)*exp(-z^2), z=-infinity..infinity) assuming k::real;

(1/2)*(-1)^k*Pi^(1/2)+(1/2)*Pi^(1/2)

 (2.3)
> 

int(2*abs(sin(x*p)*sin(x)), x = 0 .. Pi) assuming p> 1;

-2*(sin(Pi*p)*signum(sin(Pi*p))*cos(Pi/p)-p*sin(Pi/p)*cos(Pi*(floor(p)+1)/p)+sin(Pi*(floor(p)+1)/p)*cos(Pi/p)*p-sin(Pi*p)*signum(sin(Pi*p))-sin(Pi*(floor(p)+1)/p)*p+sin(Pi/p)*p)/((cos(Pi/p)-1)*(p^2-1))

 (2.4)
> 

int(1/(x^4-x+1), x = 0 .. infinity);

-(sum(ln(-_R)/(4*_R^3-1), _R = RootOf(_Z^4-_Z+1)))

 (2.5)


In Maple 2016, this multiple integral is computed over 3 times faster than it was in Maple 2015.

> 

int(exp(abs(x1-x2))*exp(abs(x1-x3))*exp(abs(x3-x4))*exp(abs(x4-x2)), [x1=0..R, x2=0..R, x3=0..R, x4=0..R], AllSolutions) assuming R>0;

(1/8)*exp(4*R)-29/8+(7/2)*exp(2*R)-5*R*exp(2*R)+2*exp(2*R)*R^2-(5/2)*R

 (2.6)

Austin Roche
Mathematical Software, Maplesoft

Integration Variables in Maple...

aroche 305
integration
November 14 2014
2 4

A customer on Twitter recently asked why Maple gives the following result:

 

 


The issue here is that the t in f(t) is the same as the integration variable. 140 characters is not a lot to work with for a reply, so here is a longer explanation.

 

First, note that the process of integration treats the integration variable differently than the other variables, so that replacing another variable by the integration variable has a different effect depending on whether the replacement is done before or after the integration is performed. Consider this simple example:

 

a := int(t, t)

(1/2)*t^2

 (4)

eval(a, t = x)

(1/2)*x^2

 (5)

a := int(x, t)

x*t

 (6)

   

eval(a, t = x)

x^2

 (7)

 

In other words, integration does not commute with substitution. This is a fundamental property of integration and in fact, Maple's eval has special rules to take this into account when you ask it to replace the integration variable.  For example, if you evaluate the inert form of the integral at x = y, the substitution is performed explicitly:

 

 

eval(Int(x-t, t = 0 .. x), x = y)

Int(y-t, t = 0 .. y)

 (8)

value(Int(y-t, t = 0 .. y))

(1/2)*y^2

 (9)

 

However, if you try to evaluate at x = t, the evaluation is delayed until after the integral is evaluated:

 

eval(Int(x-t, t = 0 .. x), x = t)

eval(Int(x-t, t = 0 .. x), {x = t})

 (10)

 

value(eval(Int(x-t, t = 0 .. x), {x = t}))

(1/2)*t^2

 (11)

 

The eval command knows it shouldn't substitute into an integral when the substitution involves the variable of integration.

 

However, in the user's example, asking Maple for f(t) is equivalent to substitution directly before the integration is performed, like this:

 

subs(x = t, Int(x-t, t = 0 .. x))

Int(0, t = 0 .. t)

 (12)

which of course gives:

 

value(%)

0

 (13)

 

Another way to have the two t variables be considered distinct is to explicitly make the integration variable a dummy by declaring it local:

 

f := proc (x) local t; int(x-t, t = 0 .. x) end proc
 

Now the ts are treated differently:

 

f(t)

(1/2)*t^2

 (14)

``

Austin Roche

Senior Math Developer

Maplesoft

 

Download integration_variables.mw

Page 1 of 1