f:= (x,a)->`if` (x <a,0,(x-a)^2);
plot3d(f(x,a),x=0..3,a=0..3);

Explore(plot(f(x,a),x=0..3),parameters=[a=0..3]);

See also Kitonum's answer in

http://www.mapleprimes.com/questions/202859-To-Plot-Procedure

>restart;
>tan(arctan(-1) - 30*Pi/180);
>evalf(%);

-3.7320508080

>tan(arctan(-1) - 45*Pi/180);

-infinity-infinity*I

>evalf(%)

-Float(infinity)-Float(infinity)*I

I don't know why maple returns the value as a complex number.

But, as arctan(-1) - 45*Pi/180 is (-1/2)*Pi,

its tangent is minus infinity.

With g(2), maple tried to calculate diff(f(2),2), which the error message shows.

So, there is a way to calculate diff(f(x),x) and then evaluate it at x=2, that is,

eval(g(x),x=2);

taro

P.S.

Thank Carl for telling me the way to use D. I didn't know it.

To change the form of worksheet mode into 2D in the document mode, you have to change it after you transferred it to

the screen in the document mode, like this: right click->2D math->Convert->2Dmath.

Inversely, to see 2D expression in a screen of the worksheet mode, you have to make a document block with create a document block in the edit in menu, then after pasting the expression you want to move in, change the form with the right click->

2D math->Convert->2Dmath.

A difference between the document mode and the worksheet mode is whether the document block is a default or not.

Hello nm,

I typed that code, finding it generated error message, of course. % before "," is  missed, surely.

f:=(x,y,z)->x*y*z;

B:={1,3,4};

f(op(B));

s:=n->k*(1-a^(n+1))*u(n);
eval(s(3),{k=4,d=5});
eval(s(3),d=5);
eval(s(3),k=5);
eval(s(3),d=3);
subs({k=4,d=5},s(3));

For both cases of subs and eval, k above is not assigned to any value. So, after the outcome of the second line,

that of the third line becomes k*(-a^4+1)*u(3).

The different of uses of subs and evaluate is only that the former substitute the value not evaluating anything,

while the latter substitute the value to the expression after evaluation is done.

Another way is that of not using control + T. After the >, you can type #, which has red color.

Then, after typing fn+F5, which changes maple to math mode, you can write in sentences or expressions.

On the other hand, if you type # after you changed to math mode with fn+F5, or if you use control + T,

problems occur.

taro 

My answer is following. But, it is the same as what you write, that is, replacing omega*T0+phi as a constant and

after calculation, put back the original expression for the constant, isn't it.

@sunit 

I'm sorry. This works.

>a:=sin(omega*T0+phi-T);
                   -sin(-T0 omega + T - phi)
>algsubs(omega*T0+phi=freeze(omega*T0+phi),a);
                      -sin(-freeze/R0 + T)
>expand(%);
         sin(freeze/R0) cos(T) - cos(freeze/R0) sin(T)
>thaw(%);

taro

with maple2015, it became true

aa:=sqrt(sqrt(9)*sqrt((1+(b+1)^2*c^2+((10/3)*b-2)*c)*(1+(b+1)^2*c^2+(2*b-2)*c))+3+(3*b^2+6*b+3)*c^2+(8*b-6)*c) assuming(b::positive,c::positive);

coulditbe(aa::positive);

true

Once, probably as similarly as you, I had an experience that I couldn't open a file written in the past

with the extention "ms" not recent "mw", trying to open it through file->open just to find that

the icon of that file have light color showing that it couldn't be opened. I couldn't open that file

with double click as well.

In the end, I could open it, but it through the way that into the screen of Maple I drag and dropped that file.

Did you try this?

taro

s := solve(x^2-3*x+2 = 0, x);
                              2, 1
assign(('a','b')=(s[1],s[2]));

This might be a silly answer.

restart;
f(x) = x + 6*x + 12;
                        f(x) = 7 x + 12
assign(%);

                            7 x + 12
g:=unapply(f(x)*exp(x),x);
x -> (7 x + 12) exp(x)
g(2);
                           26 exp(2)
f(x);
                            7 x + 12

The use of g:=x->f(x)*exp(x) instead of g:=unapply(f(x)*exp(x),x) doesn't work as ->doesn't evaluate

f(x) as 7*x+2.

Your original problem was that f(x) = x  + 6 x + 12 was not assignment of the rhs to f(x).

taro