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Transforms the expression expr by giving each summation and product a
unique index. This gives changevar greater precision when it is working
with summations or products. The form of the unique index is
jnumber. The quantity number is determined by referring to
gensumnum, which can be changed by the user. For example,
gensumnum:0$ resets it.
Represents the sum of expr for each element x in L.
A noun form 'lsum is returned if the argument L does not evaluate
to a list.
Examples:
(%i1) lsum (x^i, i, [1, 2, 7]);
7 2
(%o1) x + x + x
(%i2) lsum (i^2, i, rootsof (x^3 - 1, x));
====
\ 2
(%o2) > i
/
====
3
i in rootsof(x - 1, x)
Moves multiplicative factors outside a summation to inside.
If the index is used in the
outside expression, then the function tries to find a reasonable
index, the same as it does for sumcontract. This is essentially the
reverse idea of the outative property of summations, but note that it
does not remove this property, it only bypasses it.
In some cases, a scanmap (multthru, expr) may be necessary before
the intosum.
Default value: false
When simpproduct is true, the result of a product is simplified.
This simplification may sometimes be able to produce a closed form. If
simpproduct is false or if the quoted form 'product is used, the
value is a product noun form which is a representation of the pi notation used
in mathematics.
Represents a product of the values of expr as
the index i varies from i_0 to i_1.
The noun form 'product is displayed as an uppercase letter pi.
product evaluates expr and lower and upper limits i_0 and
i_1, product quotes (does not evaluate) the index i.
If the upper and lower limits differ by an integer, expr is evaluated for each value of the index i, and the result is an explicit product.
Otherwise, the range of the index is indefinite.
Some rules are applied to simplify the product.
When the global variable simpproduct is true, additional rules
are applied. In some cases, simplification yields a result which is not a
product; otherwise, the result is a noun form 'product.
Examples:
(%i1) product (x + i*(i+1)/2, i, 1, 4);
(%o1) (x + 1) (x + 3) (x + 6) (x + 10)
(%i2) product (i^2, i, 1, 7);
(%o2) 25401600
(%i3) product (a[i], i, 1, 7);
(%o3) a a a a a a a
1 2 3 4 5 6 7
(%i4) product (a(i), i, 1, 7);
(%o4) a(1) a(2) a(3) a(4) a(5) a(6) a(7)
(%i5) product (a(i), i, 1, n);
n
/===\
! !
(%o5) ! ! a(i)
! !
i = 1
(%i6) product (k, k, 1, n);
n
/===\
! !
(%o6) ! ! k
! !
k = 1
(%i7) product (k, k, 1, n), simpproduct;
(%o7) n!
(%i8) product (integrate (x^k, x, 0, 1), k, 1, n);
n
/===\
! ! 1
(%o8) ! ! -----
! ! k + 1
k = 1
(%i9) product (if k <= 5 then a^k else b^k, k, 1, 10);
15 40
(%o9) a b
Default value: false
When simpsum is true, the result of a sum is simplified.
This simplification may sometimes be able to produce a closed form. If
simpsum is false or if the quoted form 'sum is used, the
value is a sum noun form which is a representation of the sigma notation used
in mathematics.
Represents a summation of the values of expr as
the index i varies from i_0 to i_1.
The noun form 'sum is displayed as an uppercase letter sigma.
sum evaluates its summand expr and lower and upper limits i_0
and i_1, sum quotes (does not evaluate) the index i.
If the upper and lower limits differ by an integer, the summand expr is evaluated for each value of the summation index i, and the result is an explicit sum.
Otherwise, the range of the index is indefinite.
Some rules are applied to simplify the summation.
When the global variable simpsum is true, additional rules are
applied. In some cases, simplification yields a result which is not a
summation; otherwise, the result is a noun form 'sum.
When the evflag (evaluation flag) cauchysum is true,
a product of summations is expressed as a Cauchy product,
in which the index of the inner summation is a function of the
index of the outer one, rather than varying independently.
The global variable genindex is the alphabetic prefix used to generate
the next index of summation, when an automatically generated index is needed.
gensumnum is the numeric suffix used to generate the next index of
summation, when an automatically generated index is needed.
When gensumnum is false, an automatically-generated index is only
genindex with no numeric suffix.
See also lsum, sumcontract, intosum,
bashindices, niceindices,
nouns, evflag, and Package zeilberger
Examples:
(%i1) sum (i^2, i, 1, 7);
(%o1) 140
(%i2) sum (a[i], i, 1, 7);
(%o2) a + a + a + a + a + a + a
7 6 5 4 3 2 1
(%i3) sum (a(i), i, 1, 7);
(%o3) a(7) + a(6) + a(5) + a(4) + a(3) + a(2) + a(1)
(%i4) sum (a(i), i, 1, n);
n
====
\
(%o4) > a(i)
/
====
i = 1
(%i5) sum (2^i + i^2, i, 0, n);
n
====
\ i 2
(%o5) > (2 + i )
/
====
i = 0
(%i6) sum (2^i + i^2, i, 0, n), simpsum;
3 2
n + 1 2 n + 3 n + n
(%o6) 2 + --------------- - 1
6
(%i7) sum (1/3^i, i, 1, inf);
inf
====
\ 1
(%o7) > --
/ i
==== 3
i = 1
(%i8) sum (1/3^i, i, 1, inf), simpsum;
1
(%o8) -
2
(%i9) sum (i^2, i, 1, 4) * sum (1/i^2, i, 1, inf);
inf
====
\ 1
(%o9) 30 > --
/ 2
==== i
i = 1
(%i10) sum (i^2, i, 1, 4) * sum (1/i^2, i, 1, inf), simpsum;
2
(%o10) 5 %pi
(%i11) sum (integrate (x^k, x, 0, 1), k, 1, n);
n
====
\ 1
(%o11) > -----
/ k + 1
====
k = 1
(%i12) sum (if k <= 5 then a^k else b^k, k, 1, 10);
10 9 8 7 6 5 4 3 2
(%o12) b + b + b + b + b + a + a + a + a + a
Combines all sums of an addition that have
upper and lower bounds that differ by constants. The result is an
expression containing one summation for each set of such summations
added to all appropriate extra terms that had to be extracted to form
this sum. sumcontract combines all compatible sums and uses one of
the indices from one of the sums if it can, and then try to form a
reasonable index if it cannot use any supplied.
It may be necessary to do an intosum (expr) before the
sumcontract.
Default value: false
When sumexpand is true, products of sums and
exponentiated sums simplify to nested sums.
See also cauchysum.
Examples:
(%i1) sumexpand: true$ (%i2) sum (f (i), i, 0, m) * sum (g (j), j, 0, n);
m n
==== ====
\ \
(%o2) > > f(i1) g(i2)
/ /
==== ====
i1 = 0 i2 = 0
(%i3) sum (f (i), i, 0, m)^2;
m m
==== ====
\ \
(%o3) > > f(i3) f(i4)
/ /
==== ====
i3 = 0 i4 = 0
Next: Functions and Variables for Series, Previous: Functions and Variables for Sums and Products, Up: Sums, Products, and Series [Contents][Index]
Maxima contains functions taylor and powerseries for finding the
series of differentiable functions. It also has tools such as nusum
capable of finding the closed form of some series. Operations such as addition
and multiplication work as usual on series. This section presents the global
variables which control the expansion.
Next: Introduction to Fourier series, Previous: Introduction to Series, Up: Sums, Products, and Series [Contents][Index]
Default value: false
When multiplying together sums with inf as their upper limit,
if sumexpand is true and cauchysum is true
then the Cauchy product will be used rather than the usual
product.
In the Cauchy product the index of the inner summation is a
function of the index of the outer one rather than varying
independently.
Example:
(%i1) sumexpand: false$ (%i2) cauchysum: false$
(%i3) s: sum (f(i), i, 0, inf) * sum (g(j), j, 0, inf);
inf inf
==== ====
\ \
(%o3) ( > f(i)) > g(j)
/ /
==== ====
i = 0 j = 0
(%i4) sumexpand: true$ (%i5) cauchysum: true$
(%i6) expand(s,0,0);
inf i1
==== ====
\ \
(%o6) > > g(i1 - i2) f(i2)
/ /
==== ====
i1 = 0 i2 = 0
For each function f_i of one variable x_i,
deftaylor defines expr_i as the Taylor series about zero.
expr_i is typically a polynomial in x_i or a summation;
more general expressions are accepted by deftaylor without complaint.
powerseries (f_i(x_i), x_i, 0)
returns the series defined by deftaylor.
deftaylor returns a list of the functions f_1, …, f_n.
deftaylor evaluates its arguments.
Example:
(%i1) deftaylor (f(x), x^2 + sum(x^i/(2^i*i!^2), i, 4, inf));
(%o1) [f]
(%i2) powerseries (f(x), x, 0);
inf
==== i1
\ x 2
(%o2) > -------- + x
/ i1 2
==== 2 i1!
i1 = 4
(%i3) taylor (exp (sqrt (f(x))), x, 0, 4);
2 3 4
x 3073 x 12817 x
(%o3)/T/ 1 + x + -- + ------- + -------- + . . .
2 18432 307200
Default value: true
When maxtayorder is true, then during algebraic
manipulation of (truncated) Taylor series, taylor tries to retain
as many terms as are known to be correct.
Renames the indices of sums and products in expr. niceindices
attempts to rename each index to the value of niceindicespref[1], unless
that name appears in the summand or multiplicand, in which case
niceindices tries the succeeding elements of niceindicespref in
turn, until an unused variable is found. If the entire list is exhausted,
additional indices are constructed by appending integers to the value of
niceindicespref[1], e.g., i0, i1, i2, …
niceindices returns an expression.
niceindices evaluates its argument.
Example:
(%i1) niceindicespref;
(%o1) [i, j, k, l, m, n]
(%i2) product (sum (f (foo + i*j*bar), foo, 1, inf), bar, 1, inf);
inf inf
/===\ ====
! ! \
(%o2) ! ! > f(bar i j + foo)
! ! /
bar = 1 ====
foo = 1
(%i3) niceindices (%);
inf inf
/===\ ====
! ! \
(%o3) ! ! > f(i j l + k)
! ! /
l = 1 ====
k = 1
Default value: [i, j, k, l, m, n]
niceindicespref is the list from which niceindices
takes the names of indices for sums and products.
The elements of niceindicespref are must be names of simple variables.
Example:
(%i1) niceindicespref: [p, q, r, s, t, u]$
(%i2) product (sum (f (foo + i*j*bar), foo, 1, inf), bar, 1, inf);
inf inf
/===\ ====
! ! \
(%o2) ! ! > f(bar i j + foo)
! ! /
bar = 1 ====
foo = 1
(%i3) niceindices (%);
inf inf
/===\ ====
! ! \
(%o3) ! ! > f(i j q + p)
! ! /
q = 1 ====
p = 1
Carries out indefinite hypergeometric summation of expr with respect to x using a decision procedure due to R.W. Gosper. expr and the result must be expressible as products of integer powers, factorials, binomials, and rational functions.
The terms "definite"
and "indefinite summation" are used analogously to "definite" and
"indefinite integration".
To sum indefinitely means to give a symbolic result
for the sum over intervals of variable length, not just e.g. 0 to
inf. Thus, since there is no formula for the general partial sum of
the binomial series, nusum can’t do it.
nusum and unsum know a little about sums and differences of
finite products. See also unsum.
Examples:
(%i1) nusum (n*n!, n, 0, n);
Dependent equations eliminated: (1)
(%o1) (n + 1)! - 1
(%i2) nusum (n^4*4^n/binomial(2*n,n), n, 0, n);
4 3 2 n
2 (n + 1) (63 n + 112 n + 18 n - 22 n + 3) 4 2
(%o2) ------------------------------------------------ - ------
693 binomial(2 n, n) 3 11 7
(%i3) unsum (%, n);
4 n
n 4
(%o3) ----------------
binomial(2 n, n)
(%i4) unsum (prod (i^2, i, 1, n), n);
n - 1
/===\
! ! 2
(%o4) ( ! ! i ) (n - 1) (n + 1)
! !
i = 1
(%i5) nusum (%, n, 1, n);
Dependent equations eliminated: (2 3)
n
/===\
! ! 2
(%o5) ! ! i - 1
! !
i = 1
Returns a list of all rational functions which have the given Taylor series expansion where the sum of the degrees of the numerator and the denominator is less than or equal to the truncation level of the power series, i.e. are "best" approximants, and which additionally satisfy the specified degree bounds.
taylor_series is an univariate Taylor series. numer_deg_bound and denom_deg_bound are positive integers specifying degree bounds on the numerator and denominator.
taylor_series can also be a Laurent series, and the degree
bounds can be inf which causes all rational functions whose total
degree is less than or equal to the length of the power series to be
returned. Total degree is defined as numer_deg_bound +
denom_deg_bound.
Length of a power series is defined as
"truncation level" + 1 - min(0, "order of series").
(%i1) taylor (1 + x + x^2 + x^3, x, 0, 3);
2 3
(%o1)/T/ 1 + x + x + x + . . .
(%i2) pade (%, 1, 1);
1
(%o2) [- -----]
x - 1
(%i3) t: taylor(-(83787*x^10 - 45552*x^9 - 187296*x^8
+ 387072*x^7 + 86016*x^6 - 1507328*x^5
+ 1966080*x^4 + 4194304*x^3 - 25165824*x^2
+ 67108864*x - 134217728)
/134217728, x, 0, 10);
2 3 4 5 6 7
x 3 x x 15 x 23 x 21 x 189 x
(%o3)/T/ 1 - - + ---- - -- - ----- + ----- - ----- - ------
2 16 32 1024 2048 32768 65536
8 9 10
5853 x 2847 x 83787 x
+ ------- + ------- - --------- + . . .
4194304 8388608 134217728
(%i4) pade (t, 4, 4);
(%o4) []
There is no rational function of degree 4 numerator/denominator, with this power series expansion. You must in general have degree of the numerator and degree of the denominator adding up to at least the degree of the power series, in order to have enough unknown coefficients to solve.
(%i5) pade (t, 5, 5);
5 4 3
(%o5) [- (520256329 x - 96719020632 x - 489651410240 x
2
- 1619100813312 x - 2176885157888 x - 2386516803584)
5 4 3
/(47041365435 x + 381702613848 x + 1360678489152 x
2
+ 2856700692480 x + 3370143559680 x + 2386516803584)]
Returns the general form of the power series expansion for expr in the
variable x about the point a (which may be inf for infinity):
inf
====
\ n
> b (x - a)
/ n
====
n = 0
If powerseries is unable to expand expr,
taylor may give the first several terms of the series.
When verbose is true,
powerseries prints progress messages.
(%i1) verbose: true$
(%i2) powerseries (log(sin(x)/x), x, 0);
can't expand
log(sin(x))
so we'll try again after applying the rule:
d
/ -- (sin(x))
[ dx
log(sin(x)) = i ----------- dx
] sin(x)
/
in the first simplification we have returned:
/
[
i cot(x) dx - log(x)
]
/
inf
==== i1 2 i1 2 i1
\ (- 1) 2 bern(2 i1) x
> ------------------------------
/ i1 (2 i1)!
====
i1 = 1
(%o2) -------------------------------------
2
Default value: false
When psexpand is true,
an extended rational function expression is displayed fully expanded.
The switch ratexpand has the same effect.
When psexpand is false,
a multivariate expression is displayed just as in the rational function package.
When psexpand is multi,
then terms with the same total degree in the variables are grouped together.
These functions return the reversion of expr, a Taylor series about zero
in the variable x. revert returns a polynomial of degree equal to
the highest power in expr. revert2 returns a polynomial of degree
n, which may be greater than, equal to, or less than the degree of
expr.
load ("revert") loads these functions.
Examples:
(%i1) load ("revert")$
(%i2) t: taylor (exp(x) - 1, x, 0, 6);
2 3 4 5 6
x x x x x
(%o2)/T/ x + -- + -- + -- + --- + --- + . . .
2 6 24 120 720
(%i3) revert (t, x);
6 5 4 3 2
10 x - 12 x + 15 x - 20 x + 30 x - 60 x
(%o3)/R/ - --------------------------------------------
60
(%i4) ratexpand (%);
6 5 4 3 2
x x x x x
(%o4) - -- + -- - -- + -- - -- + x
6 5 4 3 2
(%i5) taylor (log(x+1), x, 0, 6);
2 3 4 5 6
x x x x x
(%o5)/T/ x - -- + -- - -- + -- - -- + . . .
2 3 4 5 6
(%i6) ratsimp (revert (t, x) - taylor (log(x+1), x, 0, 6));
(%o6) 0
(%i7) revert2 (t, x, 4);
4 3 2
x x x
(%o7) - -- + -- - -- + x
4 3 2
taylor (expr, x, a, n) expands the expression
expr in a truncated Taylor or Laurent series in the variable x
around the point a,
containing terms through (x - a)^n.
If expr is of the form f(x)/g(x) and
g(x) has no terms up to degree n then taylor
attempts to expand g(x) up to degree 2 n.
If there are still no nonzero terms, taylor doubles the degree of the
expansion of g(x) so long as the degree of the expansion is
less than or equal to n 2^taylordepth.
taylor (expr, [x_1, x_2, ...], a, n)
returns a truncated power series
of degree n in all variables x_1, x_2, …
about the point (a, a, ...).
taylor (expr, [x_1, a_1, n_1], [x_2,
a_2, n_2], ...) returns a truncated power series in the variables
x_1, x_2, … about the point
(a_1, a_2, ...), truncated at n_1, n_2, …
taylor (expr, [x_1, x_2, ...], [a_1,
a_2, ...], [n_1, n_2, ...]) returns a truncated power series
in the variables x_1, x_2, … about the point
(a_1, a_2, ...), truncated at n_1, n_2, …
taylor (expr, [x, a, n, 'asymp]) returns an
expansion of expr in negative powers of x - a.
The highest order term is (x - a)^-n.
When maxtayorder is true, then during algebraic
manipulation of (truncated) Taylor series, taylor tries to retain
as many terms as are known to be correct.
When psexpand is true,
an extended rational function expression is displayed fully expanded.
The switch ratexpand has the same effect.
When psexpand is false,
a multivariate expression is displayed just as in the rational function package.
When psexpand is multi,
then terms with the same total degree in the variables are grouped together.
See also the taylor_logexpand switch for controlling expansion.
Examples:
(%i1) taylor (sqrt (sin(x) + a*x + 1), x, 0, 3);
2 2
(a + 1) x (a + 2 a + 1) x
(%o1)/T/ 1 + --------- - -----------------
2 8
3 2 3
(3 a + 9 a + 9 a - 1) x
+ -------------------------- + . . .
48
(%i2) %^2;
3
x
(%o2)/T/ 1 + (a + 1) x - -- + . . .
6
(%i3) taylor (sqrt (x + 1), x, 0, 5);
2 3 4 5
x x x 5 x 7 x
(%o3)/T/ 1 + - - -- + -- - ---- + ---- + . . .
2 8 16 128 256
(%i4) %^2;
(%o4)/T/ 1 + x + . . .
(%i5) product ((1 + x^i)^2.5, i, 1, inf)/(1 + x^2);
inf
/===\
! ! i 2.5
! ! (x + 1)
! !
i = 1
(%o5) -----------------
2
x + 1
(%i6) ev (taylor(%, x, 0, 3), keepfloat);
2 3
(%o6)/T/ 1 + 2.5 x + 3.375 x + 6.5625 x + . . .
(%i7) taylor (1/log (x + 1), x, 0, 3);
2 3
1 1 x x 19 x
(%o7)/T/ - + - - -- + -- - ----- + . . .
x 2 12 24 720
(%i8) taylor (cos(x) - sec(x), x, 0, 5);
4
2 x
(%o8)/T/ - x - -- + . . .
6
(%i9) taylor ((cos(x) - sec(x))^3, x, 0, 5);
(%o9)/T/ 0 + . . .
(%i10) taylor (1/(cos(x) - sec(x))^3, x, 0, 5);
2 4
1 1 11 347 6767 x 15377 x
(%o10)/T/ - -- + ---- + ------ - ----- - ------- - --------
6 4 2 15120 604800 7983360
x 2 x 120 x
+ . . .
(%i11) taylor (sqrt (1 - k^2*sin(x)^2), x, 0, 6);
2 2 4 2 4
k x (3 k - 4 k ) x
(%o11)/T/ 1 - ----- - ----------------
2 24
6 4 2 6
(45 k - 60 k + 16 k ) x
- -------------------------- + . . .
720
(%i12) taylor ((x + 1)^n, x, 0, 4);
2 2 3 2 3
(n - n) x (n - 3 n + 2 n) x
(%o12)/T/ 1 + n x + ----------- + --------------------
2 6
4 3 2 4
(n - 6 n + 11 n - 6 n) x
+ ---------------------------- + . . .
24
(%i13) taylor (sin (y + x), x, 0, 3, y, 0, 3);
3 2
y y
(%o13)/T/ y - -- + . . . + (1 - -- + . . .) x
6 2
3 2
y y 2 1 y 3
+ (- - + -- + . . .) x + (- - + -- + . . .) x + . . .
2 12 6 12
(%i14) taylor (sin (y + x), [x, y], 0, 3);
3 2 2 3
x + 3 y x + 3 y x + y
(%o14)/T/ y + x - ------------------------- + . . .
6
(%i15) taylor (1/sin (y + x), x, 0, 3, y, 0, 3);
1 y 1 1 1 2
(%o15)/T/ - + - + . . . + (- -- + - + . . .) x + (-- + . . .) x
y 6 2 6 3
y y
1 3
+ (- -- + . . .) x + . . .
4
y
(%i16) taylor (1/sin (y + x), [x, y], 0, 3);
3 2 2 3
1 x + y 7 x + 21 y x + 21 y x + 7 y
(%o16)/T/ ----- + ----- + ------------------------------- + . . .
x + y 6 360
Default value: 3
If there are still no nonzero terms, taylor doubles the degree of the
expansion of g(x) so long as the degree of the expansion is
less than or equal to n 2^taylordepth.
Returns information about the Taylor series expr. The return value is a list of lists. Each list comprises the name of a variable, the point of expansion, and the degree of the expansion.
taylorinfo returns false if expr is not a Taylor series.
Example:
(%i1) taylor ((1 - y^2)/(1 - x), x, 0, 3, [y, a, inf]);
2 2
(%o1)/T/ - (y - a) - 2 a (y - a) + (1 - a )
2 2
+ (1 - a - 2 a (y - a) - (y - a) ) x
2 2 2
+ (1 - a - 2 a (y - a) - (y - a) ) x
2 2 3
+ (1 - a - 2 a (y - a) - (y - a) ) x + . . .
(%i2) taylorinfo(%);
(%o2) [[y, a, inf], [x, 0, 3]]
Returns true if expr is a Taylor series,
and false otherwise.
Default value: true
taylor_logexpand controls expansions of logarithms in
taylor series.
When taylor_logexpand is true, all logarithms are expanded fully
so that zero-recognition problems involving logarithmic identities do not
disturb the expansion process. However, this scheme is not always
mathematically correct since it ignores branch information.
When taylor_logexpand is set to false, then the only expansion of
logarithms that occur is that necessary to obtain a formal power series.
Default value: true
taylor_order_coefficients controls the ordering of
coefficients in a Taylor series.
When taylor_order_coefficients is true,
coefficients of taylor series are ordered canonically.
Simplifies coefficients of the power series expr.
taylor calls this function.
Default value: true
When taylor_truncate_polynomials is true,
polynomials are truncated based upon the input truncation levels.
Otherwise,
polynomials input to taylor are considered to have infinite precision.
Converts expr from taylor form to canonical rational expression
(CRE) form. The effect is the same as rat (ratdisrep (expr)), but
faster.
Annotates the internal representation of the general expression expr so that it is displayed as if its sums were truncated Taylor series. expr is not otherwise modified.
Example:
(%i1) expr: x^2 + x + 1;
2
(%o1) x + x + 1
(%i2) trunc (expr);
2
(%o2) 1 + x + x + . . .
(%i3) is (expr = trunc (expr));
(%o3) true
Returns the first backward difference
f(n) - f(n - 1).
Thus unsum in a sense is the inverse of sum.
See also nusum.
Examples:
(%i1) g(p) := p*4^n/binomial(2*n,n);
n
p 4
(%o1) g(p) := ----------------
binomial(2 n, n)
(%i2) g(n^4);
4 n
n 4
(%o2) ----------------
binomial(2 n, n)
(%i3) nusum (%, n, 0, n);
4 3 2 n
2 (n + 1) (63 n + 112 n + 18 n - 22 n + 3) 4 2
(%o3) ------------------------------------------------ - ------
693 binomial(2 n, n) 3 11 7
(%i4) unsum (%, n);
4 n
n 4
(%o4) ----------------
binomial(2 n, n)
Default value: false
When verbose is true,
powerseries prints progress messages.
Next: Functions and Variables for Fourier series, Previous: Functions and Variables for Series, Up: Sums, Products, and Series [Contents][Index]
The fourie package comprises functions for the symbolic computation
of Fourier series.
There are functions in the fourie package to calculate Fourier integral
coefficients and some functions for manipulation of expressions.
Next: Functions and Variables for Poisson series, Previous: Introduction to Fourier series, Up: Sums, Products, and Series [Contents][Index]
Returns true if equal (x, y) otherwise false
(doesn’t give an error message like equal (x, y) would do in this case).
remfun (f, expr) replaces all occurrences of f
(arg) by arg in expr.
remfun (f, expr, x) replaces all occurrences of
f (arg) by arg in expr only if arg contains
the variable x.
funp (f, expr)
returns true if expr contains the function f.
funp (f, expr, x)
returns true if expr contains the function f and the variable
x is somewhere in the argument of one of the instances of f.
absint (f, x, halfplane)
returns the indefinite integral of f with respect to
x in the given halfplane (pos, neg, or both).
f may contain expressions of the form
abs (x), abs (sin (x)), abs (a) * exp (-abs (b) * abs (x)).
absint (f, x) is equivalent to
absint (f, x, pos).
absint (f, x, a, b) returns the definite integral
of f with respect to x from a to b.
f may include absolute values.
Returns a list of the Fourier coefficients of f(x) defined
on the interval [-p, p].
Simplifies sin (n %pi) to 0 if sinnpiflag is true and
cos (n %pi) to (-1)^n if cosnpiflag is true.
Default value: true
See foursimp.
Default value: true
See foursimp.
Constructs and returns the Fourier series from the list of Fourier coefficients
l up through limit terms (limit may be inf). x
and p have same meaning as in fourier.
Returns the Fourier cosine coefficients for f(x) defined on
[0, p].
Returns the Fourier sine coefficients for f(x) defined on
[0, p].
Returns fourexpand (foursimp (fourier (f, x, p)),
x, p, 'inf).
Constructs and returns a list of the Fourier integral coefficients of
f(x) defined on [minf, inf].
Returns the Fourier cosine integral coefficients for f(x)
on [0, inf].
Returns the Fourier sine integral coefficients for f(x) on
[0, inf].
Previous: Functions and Variables for Fourier series, Up: Sums, Products, and Series [Contents][Index]
Converts a into a Poisson encoding.
Converts a from Poisson encoding to general representation. If a is
not in Poisson form, outofpois carries out the conversion,
i.e., the return value is outofpois (intopois (a)).
This function is thus a canonical simplifier
for sums of powers of sine and cosine terms of a particular type.
Differentiates a with respect to b. b must occur only in the trig arguments or only in the coefficients.
Functionally identical to intopois (a^b).
b must be a positive integer.
Integrates in a similarly restricted sense (to poisdiff). Non-periodic
terms in b are dropped if b is in the trig arguments.
Default value: 5
poislim determines the domain of the coefficients in
the arguments of the trig functions. The initial value of 5
corresponds to the interval [-2^(5-1)+1,2^(5-1)], or [-15,16], but it
can be set to [-2^(n-1)+1, 2^(n-1)].
will map the functions sinfn on the sine terms and cosfn on the cosine terms of the Poisson series given. sinfn and cosfn are functions of two arguments which are a coefficient and a trigonometric part of a term in series respectively.
Is functionally identical to intopois (a + b).
Converts a into a Poisson series for a in general representation.
The symbol /P/ follows the line label of Poisson series
expressions.
Substitutes a for b in c. c is a Poisson series.
(1) Where B is a variable u, v, w, x, y,
or z, then a must be an expression linear in those variables (e.g.,
6*u + 4*v).
(2) Where b is other than those variables, then a must also be free of those variables, and furthermore, free of sines or cosines.
poissubst (a, b, c, d, n) is a special type
of substitution which operates on a and b as in type (1) above, but
where d is a Poisson series, expands cos(d) and
sin(d) to order n so as to provide the result of substituting
a + d for b in c. The idea is that d is an
expansion in terms of a small parameter. For example,
poissubst (u, v, cos(v), %e, 3) yields
cos(u)*(1 - %e^2/2) - sin(u)*(%e - %e^3/6).
Is functionally identical to intopois (a*b).
is a reserved function name which (if the user has defined
it) gets applied during Poisson multiplication. It is a predicate
function of 6 arguments which are the coefficients of the u, v, ..., z
in a term. Terms for which poistrim is true (for the coefficients of
that term) are eliminated during multiplication.
Prints a Poisson series in a readable format. In common
with outofpois, it will convert a into a Poisson encoding first, if
necessary.
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