8 years, 16 days

## Simple program does not work...

Maple

I have two sets

f:={1,2,3,4};

h:={1,2,4,5}

L=seq(i,i=1..4):

I want to program , if it is true that f[i] = h[i], then it prints f[i]. So the output should be {1,2}.

for i in L do
if evalb(f[i]=h[i]) then
print(f[i]);
end if;
end do;

I get no output. https://i.imgur.com/qA5hU3i.png

I tried changing the set f to list, f:= [1,2,3,4], still no output.

## Expression vs function...

Maple 2015

I am wondering why Maple does this.

> f:=x^2
> f(3)
output: x(3)^2

I understand the difference between an expression and a function. If f is an expression, shouldn't it ouput  x^2(3). Why is the output x(3)^2?

When I enter f*3 or f*(3) then I get the correct expression.

Here is a screenshot. http://prntscr.com/a7u9hm

Here is image inserted with a slightly different function

Also while I am here, what exactly does g(x):= x^2 do? when i enter g(3) I get g(3) back.

g(x) is neither a function nor an expression.

screenshot http://prntscr.com/a7ua75

## Differential operator adds space ...

Maple

Hi. I have this strange error.

Whenever I type D(f)(x) into the maple prompt, the program adds a whitespace between D(f) and (x), so I get the wrong output. I have to go back and delete the space manually. Here is a picture. http://prntscr.com/8vji4k

I type 'D(f)(x)'  and the software displays 'D(f) (x) ' in the prompt, with the extra space.

I am using maple 2015 if that helps, but I think I had the same error with Maple 18

I did not add a space. I literally just entered f:=x->x^2 -3*x + 2; D(f)(x)

but the computer adds a space as I type D(f)(x).

Also I'm not sure why the space ruins the expression

What i am supposed to get is  ' 2x - 3 '

## The collect command does not work...

Maple 2015

Why does the collect command work for some expressions and not for others. Here is a screen shot

I assume the collect command is supposed to rewrite the expression in terms of the variable descending order.

p := expand((a^2+2*x)*(a^2+2*x));
4      2        2   2
a  + 4 a  x + 4 x

collect(p, x);
4      2        2   2
a  + 4 a  x + 4 x

Does not work.

But if you look at the screenshot , it works for other expressions.

## Plotting 2d space curve ...

Maple

Hi I am reading this help document

http://www.maplesoft.com/support/help/Maple/view.aspx?path=SpaceCurve

and I cannot get maple to plot the same exact graph on that page, I receive this error

http://prntscr.com/8gzpt4

It only lets me plot 3 dimensional curves http://prntscr.com/8gzsry

When I downloaded the help document, the command executed. I cannot get it to work on my worksheet.

I even tried adding with(Student[VectorCalculus] ): and that did not help.

I am clueless why this is not working.

Is there a way to upload a maple worksheet so you can see the error.

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