The default order of a power series is 6. This can be changed either by changing the value of ORDER (analogous to DIGITS above), or by including the order in the series command. This last inclusion is optional.
>> tx:=series(tan(x),x,12); 3 5 7 9 11 x 2 x 17 x 62 x 1382 x 12 x + -- + ---- + ----- + ----- + -------- + O(x ) 3 15 315 2835 155925 >> cx:=series(cos(x),x,12); 2 4 6 8 10 x x x x x 12 1 - -- + -- - --- + ----- - ------- + O(x ) 2 24 720 40320 3628800 >> tx*cx; 3 5 7 9 11 x x x x x 12 x - -- + --- - ---- + ------ - -------- + O(x ) 6 120 5040 362880 39916800
This certainly looks like the series for sin(x), but let's see if MuPAD recognizes it as such.
>> sx:=series(sin(x),x,12): >> is(tx*cx=sx); TRUE >> type(tx*cx); PuiseuxThis means that the result of the series product is recognized by MuPAD as an object of type “Puiseux”; that is, a series possibly containing fractional powers.
MuPAD can also deal with polynomials.
>> p1:=x^8-3*x^5+11*x^4-x^2+17; 4 2 5 8 11 x - x - 3 x + x + 17 >> p2:=x^3-23*x^2-4*x+11; 3 2 x - 4 x - 23 x + 11 >> divide(p1,p2); 2 3 4 5 285641 x + 12337 x + 533 x + 23 x + x + 6613228, 2 23310861 x + 153111100 x - 72745491
The result of the last command consists of two terms: the quotient, and the remainder. MuPAD also has commands for extracting coefficients from polynomials, evaluating polynomials using Horner's algorithm, and lots more.
We shall first create a matrix domain:
>> M:=Dom::Matrix(); Dom::Matrix(Dom::ExpressionField(id, iszero))
The result returned here indicates that MuPAD expects that the elements of matrices will be members of a field for which no normalization is performed (the function id just returns elements as given), and for which 0 is recognized as the zero value.
Now we shall make all the commands in the library linalg available to us:
Now we shall create a few matrices and play with them. First, a matrix with given elements.
>> A:=M([[1,2,3],[-1,3,-2],[4,-5,2]]); +- -+ | 1, 2, 3 | | | | -1, 3, -2 | | | | 4, -5, 2 | +- -+We have entered the matrix elements as a list of lists (a list, in MuPAD, is delimited by square brackets).
Next, a matrix with elements randomly chosen to be between -9 and 9. We do this by applying the function returned by random to each of the elements.
>> B:=M(3,3,func(random(-9..9)(),i,j)); +- -+ | -7, -5, 8 | | | | 3, -1, 7 | | | | 3, -5, 6 | +- -+
Clearly this approach can be used to generate any matrix whose elements are functions of their row and column values. There is a randomMatrix command in the linalg library, but it requires the elements to be members of a coefficient ring. For our purposes, it is as easy to roll our own.
>> A*B; +- -+ | 8, -22, 40 | | | | 10, 12, 1 | | | | -37, -25, 9 | +- -+ >> det(A); -37 >> 1/A; +- -+ | 4/37, 19/37, 13/37 | | | | 6/37, 10/37, 1/37 | | | | 7/37, -13/37, -5/37 | +- -+As we have seen above, MuPAD supports operator overloading, which means that since A is a matrix, 1/A is interpreted as the inverse of A.
>> A^10; +- -+ | 19897010, -20429930, 22281963 | | | | -42711893, 43857348, -47862790 | | | | 64993856, -66730117, 72852811 | +- -+ >> b:=M(3,1,[7,9,-21]); +- -+ | 7 | | | | 9 | | | | -21 | +- -+Here the first two (optional) values give the number of rows and columns of the matrix, the matrix elements are then given in a single list. If the list isn't long enough, the remaining values will default to zero.
>> linearSolve(A,b); +- -+ | -2 | | | | 3 | | | | 1 | +- -+ >> AM:=A.b; +- -+ | 1, 2, 3, 7 | | | | -1, 3, -2, 9 | | | | 4, -5, 2, -21 | +- -+The . operator is concatenation. Again, this is an overloaded operator, as it will work for other data types as well.
>> gaussJordan(AM); +- -+ | 1, 0, 0, -2 | | | | 0, 1, 0, 3 | | | | 0, 0, 1, 1 | +- -+The linalg library is very full-featured, and contains plenty of commands for operating on matrices and vectors: row and column operations; matrix factorization and decomposition; commands for dealing with matrix polynomials and eigensystems; and so on.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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