Items tagged with curve


Suppose I want to revolve the curve given in the (X,Y)-plane by the set of parametric equations

x(t) = cos(t) + t sin(t)

y(t) = sin(t) - t cos(t)


for t in [0,Pi/2] around the X-axis. How can I plot the given surface of revolution? Similarly, the same question for

x(t) = exp(t)*cos(t)

y(t) = exp(t)*sin(t)


for t in [0,Pi/2]

I have the following Polynomial F. Computing the genus shows that this curve has negative genus and thus is reducible. But using AFactor doesn't produce a factorization. Any ideas?

F := z^9+(-3/2+(3/2*I)*sqrt(3))*y^3*z^6+(-3/2-(3/2*I)*sqrt(3))*x^3*z^6+(-3/2-(3/2*I)*sqrt(3))*y^6*z^3+(-3/2+(3/2*I)*sqrt(3))*x^6*z^3+y^9+(-3/2-(3/2*I)*sqrt(3))*x^3*y^6+(-3/2+(3/2*I)*sqrt(3))*x^6*y^3+x^9-3*(x*y*z)^3:
genus(F, x, y);

A family of curves has polar equation r=cos^n (theta/n), 0<=theta,n*pi, where n is a positive even integer.

Previously Using t = theta as the parameter and finding  a parametric form of the equation of the family of curves it was shown that 

dy/dx = (sin(t)sin(t/n)-cos(t)cos(t/n)) /( sin(t)cos(t/n)+cos(t)sin(t/n)).

Is it possible to show on Maple with a program that there are n+1 points where the tangent to the curve is paralell to the y axis?

i got 2 curves
a := abs(x);
b := (3/4)*x^2+1/4;

how can i get the max distance between them from x = -1 until x =1?


How to get tangent angle between two curves? 

example for these : f(x)=((x^4+5)^(1/2))/(sinx+5) and g(x)=cosx^2   ; x>0

thanks :)


friend i want fit a curve regarding some data and fnction and how we can find the values of a,b,c and d for the following 


X := Vector([200, 210, 220, 230, 240, 250, 260, 270, 280, 290])

Y := Vector([.4172, .3030, .4668, .3317, .1276, .1303, .1733, .1451, .3466, .4125])

     Parallel curves on surfaces. The distance between the points of the curves is measured along the curves of intersection of the surface and perpendicular planes.
     (According to tradition, it also does not make sense.)




Dear Community,

I've made a nonlinear curve fit with the Minimize routine (see attachment). What would be an easy and elegant way to rerun the model (Model) with the fitted values of a, b, c and plot the result together with the measured points in the same chart? I'm stuck here.

Tx in advance,

best regards




from mathematica,


n = 5;
CalabiYau[z_, k1_, k2_] := Module[{z1 = Exp[2Pi I k1/n]Cosh[z]^(2/n), z2 = Exp[2Pi I k2/n]Sinh[z]^(2/n)}, {Re[z1], Re[z2], Cos[alpha]Im[z1] + Sin[alpha]Im[z2]}];
Do[alpha = (0.25 + t)Pi; Show[Graphics3D[Table[ParametricPlot3D[CalabiYau[x + I y, k1, k2], {x, -1, 1}, {y, 0, Pi/2}, DisplayFunction -> Identity, Compiled ->False][[1]], {k1, 0, n - 1}, {k2, 0, n - 1}], PlotRange -> 1.5{{-1, 1}, {-1, 1}, {-1, 1}}, ViewPoint -> {1, 1, 0}]], {t, 0, 1, 0.1}];


n := 5;

z1 := exp(2*3.14*I*k1/n)*cosh(z)^(2/n);
z2 := exp(2*3.14*I*k2/n)*sinh(z)^(2/n);

alpha = (0.25 + t)Pi;

xx := Re(z1);
yy := Re(z2);
uu := cos(alpha)*Im(z1) + sin(alpha)*Im(z2);


where k1, k2, alpha are variables


i find algcurve has implicitize

how to use this implicitize to find 3d surface?

is there any other method to find?


i searched groebner basis can do this, but in mathematica is different from maple example



I am having trouble in plotting the following surface (it is a quite complicated expression, but should be fine).

OwnSurface := [-Re(arctan(exp(I*Pi*(1/4))*(u^2+v^2)^(1/2)))-(1/2)*ln((1+(u^2+v^2)^2)^(1/2)), -arctan(1/((2*(u^2+v^2))^(1/2)-1))+7*Pi*(1/4), (1/8)*ln(u^2+v^2-(2*(u^2+v^2))^(1/2)+1)-(1/8)*ln(u^2+v^2+(2*(u^2+v^2))^(1/2)+1)-(1/4)*arctan(1/((2*(u^2+v^2))^(1/2)+1))+(1/4)*arctan(1/((2*(u^2+v^2))^(1/2)-1))];

plot3d(OwnSurface, u = -.4 .. .4, v = -.4 .. .4, labels = [x1, x2, x3]);

The only thing maple does is plotting a box with a diagonal line. How can I fix this?


I want to plot a curve of the form |z*e^(1-z)| = 1 (the Szego curve). I am not sure how to call complexplot() to make this happen. Just calling complexplot(abs(z*exp(1-z)) = 1) does not work, and I don't know what else to specify. Any help?

Spiral (equidistant) around the curve.  In this case, a spiral around the spiral.
So without any sense. 
If we re-save the animation with the program Easy GIF Animator, its size is reduced by about 10 times, and sometimes much more.


I try to use a Catmull-Rom spline which has to match on several points.

I use a code extracted from the book "Geometry and curves with maple".

Here you can find an extract which is visible from google book :

I have slightly modified the initial procedure crom_2d. I didn't find the error in my procedure. May you help me to find the blocking point of my procedure ?

Here I attached my code:

Thank you for your help.

Suppose that we have the following curve on a unit sphere




which is the implicit equation of a circle in "cylindrical coorinates" (r,phi,z) on the sphere.

How can I plot this curve without solving the implicit equation for r or z ?

Also, I don't want to make any parameterization.

Suppose I have the parametric equations of a circle



where t runs from 0 to 2*pi. How can I show the orientation of this parametric curve on a plot?

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