MaplePrimes - Questions and Posts tagged with function

defining an ukhnown function

faeze — Thu, 20 Jun 2013 06:46:11 Z

I have an unkhown function as f(r) which i want to solve it at the end of calculation. How can i define it in beggining?

make function squared expression

brian bovril — Wed, 29 May 2013 07:15:59 Z

I want to write g as a function of sigma^2.

but

yields an error. how to do?

Explicit equation of arbitrary continuous piecewise linear function

Kitonum — Tue, 30 Apr 2013 16:16:55 Z

It's interesting that every continuous piecewise linear function can be specified by one explicit equation with absolute values. The procedure JoggedLine carries out such conversion.

Formal arguments of the procedure:

A - a list of the coordinates of the vertices of the polyline or the continuous piecewise linear expression defined on the entire real axis.

B (optional) - a point on the left "tail"...

Reluctance to Evaluate Erf Expression . . .

tiradentes — Fri, 26 Apr 2013 15:37:28 Z

The expression below is not producing any plot, although the axes and sliders are set :

How to plot an implicit function?

_zgj — Wed, 27 Mar 2013 06:44:40 Z

How to plot x versus theta of the following implicit function

sin(theta)-2*sin(2*x-theta+(1/3)*Pi)/sin(x+(1/3)*Pi-theta)=0

where x is the implicit function of theta

now how can I plot the relationship between x and theta(condition:-Pi<theta<Pi,-Pi<x<Pi)

Can the map command work for functions of two variables

DJJerome1976 — Tue, 26 Mar 2013 16:47:18 Z

For a function of one variable, I use the map command quite a bit to evaluate the function at several values of the independent variable. For example,

f:=x->x^2:

xlist:=[1,2,3]:

map(f,xlist)

How may I do something similar for a function of two variables? For example,

f:=(x,y)->x^2+y^2:

xylist:=[[1,1],[1,2],[2,1],[2,2]]:

Can the map command be used to evaluate f at each ordered pair? Maybe I'm not even using the correct data structure. Thanks!

Rectangular Function

digerdiga — Mon, 25 Mar 2013 12:14:58 Z

my function is:

f := proc (x) if 0 < x and x < evalf(Pi) then 1 elif evalf(Pi) < x and x < evalf(2*Pi) then -1 end if end proc

now it tried:

f1 := add((-1)^n*f(x-evalf(2*n*Pi)), n = 0 .. 10)

to get a periodic function.

but unfortunately it says:

Error, (in f) cannot determine if this expression is true or false: 0 < x and x < 3.141592654

already when trying to calc the sum.

Problem by the evaluation of a function

ssteve — Sun, 24 Mar 2013 16:12:55 Z

Good afternoon everybody,

I have a problem with the evaluation of a function. You can see the test programm I have written to test the use of functions and in the end I don't get values but the expression in letters.
I think the problem lies in the definition of g but I don't know how to solve the problem.

Thank you for your help,

ssteve

Problem with Graph

JamesK — Wed, 20 Mar 2013 21:09:36 Z

I'm trying to add the output of my function FunctionToTree,which gets all elements from an expression, to a graph using the Graph function but I'm getting erros even when I add it as a list.

with(GraphTheory):
with(SpecialGraphs):
FunctionToTree:=proc(expr)
local elem;
local Tree:=NULL;
local exprType := convert(whattype(expr),string);
local newExpr:=convert(expr,string);
if (nops(expr) <> 1) or (nops(op(1,expr)) <> 1) then
for elem in op(expr) do :

Replacing f(x) by f in an expression

Willem Ottevanger — Sun, 10 Mar 2013 06:12:32 Z

Hi,

Presently, I am trying to find a way to replace functional expressions by a variable

For example I have an expression as follows:

p:=f(x)^2 + g(x)^3

I would like to get this to look like

q:= f^2 + g^3

Does anybody have an idea of how to do this in Maple?

Thanks,

Willem

error on plotting vector field

Lalalaika — Thu, 07 Mar 2013 14:08:46 Z

Hello, I have a problem in plotting the vector field of dx/dt=sinx/sint

It shows me an error:

Error, (in DEtools/dfieldplot) unable to evaluate function `sin(x)` in evalhf

Dunno how to fix it

Here is my code:

DE := [diff(x(t), t) = sin(x)(t)/sin(t)];
with(DEtools):
DC:=[sin(x)/sin(t),.1]:
dfieldplot(DE, x(t), t = -2 .. 2, x = -1 .. 2, arrows = medium, title = 'Diff', color = DC);

Abstract multi variable expression

sebastianus — Fri, 22 Feb 2013 13:54:30 Z

Hello everybody,

I'm completely new to Maple (installed it today) and have a question about the use of multi variabele expressions. I wanted to use a function B depending from the variables a, b, c and d without describing the expression explicit.

For example: B:= (a, b, c, d); [without the -> a....]

Then I wanted to take the taylor expansion of the first order for [a=e, b=f, c=g, d=h...

when implement a new kind of differentiation, how to do like a maple diff?

williamov — Mon, 11 Feb 2013 13:16:29 Z

i am implementing q-Laplace

http://perso.uclouvain.be/alphonse.magnus/gbang/qbook712.pdf

when there are quite many differentiation rules

how to do a function for a new kind differentiation like a maple do?

plotting WKB solutions

gdog — Fri, 08 Feb 2013 15:59:44 Z

Is it possible to plot WKB solutions such as exp(-I*f(x)*x)/sqrt(f(x); where f(x) is any generic function of x e.g. sin^2x ? I have been trying in maple but can't get it to give me a plot.

Warning, expecting Range variable k blablabla... while trying to plot

digerdiga — Thu, 31 Jan 2013 17:23:35 Z

I dont know what to do any further...

I have some function containing HeunG as a function

it is of the following form

f(k)=argument(functions containing HeunG) - ln(2)*k

now plotting this works...

But when differentiating with respect to k and then plotting it gives me the following message:

Warning, expecting only range variable k in expression (I*((1/2)^(1/2*I*k))^2*HeunG(3,-9/2+3/4*I*k-3/4*k^2,-1+1/2*I*k,-1/2+1/2*I*k,1/2,1+I*k,1/2...