## How to find this function?...

F(exp(t)) = t

F(F(exp(t))) = 0

what is F ?

is it diff(ln(x),t) ?

## How to use substition with functions?...

Consider substutition with use of a function:

`subs(F(x,y)=f(x)+g(y), F(x,y));`

As expected, Maple returns the proper answer:

f(x)+g(y)

But

`subs(F(x,y)=f(x)+g(y), F(x,x));`

returns

F(x,x)

How to force Maple recognize F as a function, in order to obtain

f(x)+g(x)

in return?

The functions algsubs, applyrule work in the same way.

## differential equations with user defined function...

I would like to solve the following differential equation with a relatively complicated function that is best declared.

myfun := proc (x::float)

local output;

output := 4*x^2;

end proc;

de := diff(y(x), x)+myfun(x)*y(x) = 0.;

However, this gives the following message:

Error, invalid input: myfun expects its 1st argument, x, to be of type float, but received x

Any suggestions?

## How to get custom function name?...

If not define a procedure

just pass day(hello(a,b), c)

as parameter how to get hello , this function name and day this function name

## Function that approximates some points better...

I have to calculate a sort of trend line, but I don't know how it works with maple.
I tried with Excel.

Do you think the method is right? How can I replicate it on maple?

```Thanks in advance
```

## How to get a numerical answer using the erf functi...

I didn't even know the erf function existed until doing this problem. I looked up how to use it, so I tried plugging in the explicity form into Maple, hoping it'd solve it, but it just spit back out the erf function.

I am trying to get a number answer.  A decimal. Because this is calculating a probability. How do I get Maple to give me a number here? Thanks!

## Analyse simple function, and plot...

Hello, How to do simple analyse on function? like find intervas where function negative and positive, monotone, critical points...

And also how to plot them on one graph?

thanks :)

## how to find roots of equation J...

how to find roots of equation J0(xR) = 0 ,R is constant, using maple? I know command for zeros of Bessel function i.e J0(x) = 0.  but what to do with different argument?

## How I can plot the following function?...

O(t) = 9.2-[(8.93*35.3)/(11.17-8.93)]*(exp(-8.93*t)-exp(-11.17*t))-8.3*exp(-11.17*t)

t betwen 0 and 1

## how to solve functional equation in maple...

```ha := (diff(c(t), t))/(c(t)*(diff(c(t), t))-c(t));
solve(subs(m=ha,f(m))*subs(m=subs(c(t)=a(t),ha)), f(m)) = subs(m=ha+subs(c(t)=a(t),ha), f(m), f);```

just expect to find a function ?

## creating functions with derivatives in them. How d...

I wish to define a function which is the derivative of another function.

> f:=(x)->x^2:

> g:=(x)->diff(f(x),x):

> g(x);

2 x

> f(2);

4

> g(2);
Error, (in g) invalid input: diff received 2, which is not valid for its 2nd argument

I cannot find a way in which I can define the function g, using the functional operator, so that I can actually evaluate g(x).

How can I do this?

## how I do to obtain the Real part and the Imaginar...

I have this function:

Z := (cos((1/2)*x)-I*sin((1/2)*x))*A0/r^(1/2)+(cos((1/2)*x)+I*sin((1/2)*x))*r^(1/2)*A1+(cos(3*x*(1/2))+I*sin(3*x*(1/2)))*r^(3/2)*A2;

I wanna to obtain another function Y which equal to

Y:=f1*(Re(Z)+Re(Z'))+f2*(Im(Z)+Im(Z'));

where: f1 and f2 are constant

thanks :)