Kitonum

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11 years, 149 days

MaplePrimes Activity


These are replies submitted by Kitonum

@ActiveUser 

You wrote a lot of monotonous code, in each line of which you assign a certain expression to  g , and then do some substitution. If you think Maple is calculating something incorrectly, select only this line from the entire code and ask a specific question.

@Zen 

evalindets(g*a*(a*g+g*b+u^2*(Df-Dr))*b/(Df*Dr*(a+b)*u),`+`, t->simplify(t, {a+b=L}));

                             g*a*(L*g+u^2*(Df-Dr))*b/(u*L*Dr*Df)

@Christian Wolinski  You can have several versions of Maple at the same time in one system. On a fragment of my desktop there are labels of 4 versions (Maple 2017 in two options - Classic and Standard):

@Christian Wolinski  I do not know if this is possible. But you can always tweak Standard worksheet to make it look exactly like Classic worksheet.

@ActiveUser  Probably all your errors are related to the incorrect use of the  subs  command to substitute into the derivative that has not yet been calculated. Use the more "clever" the  eval  command for this.

See example:

A:=subs(x=1, diff(m(x),x));
B:=eval(diff(m(x),x), x=1);
m:=x->x^2;
A;
B;

                                      

 

@ActiveUser 

restart;
solve(m(x)^n=0, m(x));
diff(%, x);

                                                   0
                                                   0

@Carl Love In this case, 4 or 5 different ratings are used ( {-1, 0, 2, 3} or {-1, 0, 1, 2, 3}  ). Of course, to get an unambiguous answer, a more precise statement of the problem is required from OP.

@acer  Thanks for this observation. Take a look at the complement of my answer above.

You are trying to set a tangent to a circle passing through its center. Such a tangent does not exist and TangentLine command returns NULL.

@Ramakrishnan  You can do the same with the  geometry  package. To remove excess parts of circles you can use the  view  option:

restart;
with(plots): with(geometry):
square(Square,[point(A,0,0),point(B,0,4),point(C,4,4),point(DD,4,0)]):
circle(Circle_green,x^2+y^2=4^2, [x,y]):
circle(Circle_blue,x^2+(y-2)^2=2^2, [x,y]):
circle(Circle_red,(x-2)^2+(y-4)^2=2^2, [x,y]):
P:=draw([Square(color=black,thickness=1), Circle_green(color=green,thickness=2), Circle_blue(color=blue,thickness=2), Circle_red(color=red,thickness=2)], view=[0..4,0..4]):
Region_yellow:=inequal({y<sqrt(4^2-x^2),y>sqrt(2^2-x^2)+2}, x=0..2, y=2..4, color=yellow, nolines):
Region_pink:=inequal({y<sqrt(4^2-x^2),y>-sqrt(2^2-(x-2)^2)+4}, x=2..4, y=2..4, color=pink, nolines):
display(P, Region_yellow, Region_pink, axes=normal);

 

@Carl Love  You are right. Another example:

sum((-1)^n, n=1..infinity);
sum((-1)^n, n=1..infinity, formal);

 

@Carl Love OP wants to get  [5,2,3] , but these numbers go in different order in different lists. Therefore, I understood the question as to find common elements in these lists without taking into account the order of these elements.

@johncarl 

z := -y + sech(x - 3*t);
w := 10*sech(x - 3*t);
y1:=eval(w, [t = 0,x=-10]); 
y2:=eval(w, [t = 0,x=10]);
minimize(eval(z, t = 0),[x = -10 .. 10, y = -y1 .. y2]);
evalf(%); 
maximize(eval(z, t = 0),[x = -10 .. 10, y = -y1 .. y2]);
evalf(%); 

 

@lt00414  I didn’t understand what you can’t do? When you plot a function, you yourself specify the range for the argument. Run the following code:

E:=1/2:
Eq := -(1/2)*(diff(psi(x), x, x))+(1/2)*x^2*psi(x) = E*psi(x); 
Sol := dsolve(Eq);
plot(eval(rhs(Sol),[_C1=2,_C2=1]), x=-2..2);

@johncarl  The procedure  ContoursWithLabels  does not provide for the plotting of contours in non-rectangular areas. I think the easiest way to solve your problem is to simply add labels for the corresponding level lines  eval(z, t = 0)=C , using the  plots:-textplot  command: 


 

z := -y + sech(x - 3*t);
w := 10*sech(x - 3*t);
with(plots):
P1 := plot(eval(w, t = 0), x = -6 .. 6):
Contours:=[-7,-3,1,5,9]:
Y:=map(p->solve(eval(z,[x=1,t=0])=p,y),Contours):
P2 := contourplot(eval(z, t = 0), x = -10 .. 10, y = -eval(w, t = 0) .. eval(w, t = 0), contours = Contours, color=blue, grid = [101, 101]):
Labels:=textplot([seq([1,Y[i],C=Contours[i]], i=1..5)], color=red, font=[times,14], align=above):
display(P1,P2,Labels, size=[400,400]);

-y+sech(-x+3*t)

 

10*sech(-x+3*t)

 

 

 


 

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