SICI SPIRAL
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SICI SPIRAL
| Sici: initials of the Sine Integral (Si) and the Cosine Integral (Ci) (name given by Von Seggern in 1993).
Other name: Nielsen spiral. |
 |
Cartesian parametrization:  .
Complex parametrization:  .
Curvilinear abscissa:  .
Cartesian tangential angle:  .
Radius of curvature: 
Intrinsic equation 1:  .
Transcendental curve. |
The ordinate of the asymptote is equal to the value of the Dirichlet integral 
.
Curve very similar to the portion of hyperbolic spiral: 
.
Compare also to the Cornu spiral.
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© Robert FERRÉOL 2017