## 380 Reputation

10 years, 235 days

## simplify expression...

Maple 17

-(1/2*I)*(I*Pi*ln(2)-I*Pi*ln(g+4)-2*ln(2)^2+2*ln(2)*ln(g+4)-2*ln(2)*ln(-1/2*I)+ln(g+4)*ln(-1/2*I)-ln(g+4)*ln(2*I)+ln(-1/2*I)*ln(4-g)+ln(4-g)*ln(2*I))/Pi

why doesnt maple simplify this expression any further?

but he complains when using combine saying:

Error, (in combine/ln) second argument must be a maple type

Why is that?

## calculating with lists...

Maple 17

i have a list of numeric values like this:

r:=[a,b,c,....]

now i want to calculate the quantity

s:=lambda-r^2

which in turn should give me a list again whose entries are:

[lambda-a^2,lambda-b^2,...]

but just doing

s:=lambda-r^2 doesnt work.

lambda is an arbitrary number

## dsolve invalid input when plotting...

Maple 17

ode := diff(x(t), t, t) = 1^2*(cosh(x(t))-1)/cosh(x(t))

ics := x(0) = 2, (D(x))(0) = 0

xs := dsolve({ics, ode})

plot(xs, t = 0 .. 3)

why do i get this error?

Error, invalid input: plot expects its 1st argument, p, to be of type {set, array, list, rtable, algebraic, procedure, And(`module`, appliable)}, but received x(t) = RootOf(Int(1/(-4*arctan(exp(_a))+4*arctan(exp(2))-4+2*_a)^(1/2), _a = _Z .. 2)+t)

## Defining an algebra...

How do I define an algebra in Maple?

Say for example Quaternions:

i^2=j^2=k^2=i*j*k=-1

Thx

## series expansion factor missing?...

Maple 17

r1:=2*(1-s^2)^(1/2)*arctanh((1+s)*tanh(x)/((1-s)*(1+s))^(1/2))/((1-s)*(1+s))^(1/2)+ln((1/2)*arccosh(1/s)-x)

with x=1/2*arccosh(1/s)-beta*u

is to be calculated to the first order in u.

in fact im only interested in the first order not in the zero order.

so when applying the series I get for the first order

-beta*u/sqrt(1-s^2)

whereas by hand I get:

-beta*u*s/sqrt(1-s^2)

I'd really appreciate some idea since...

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