Some plane curvature approximations

Authors:
R. C. Mjolsness and Blair Swartz

Journal:
Math. Comp. **49** (1987), 215-230

MSC:
Primary 65D15; Secondary 65D25, 65M05, 65N05

MathSciNet review:
890263

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Abstract | References | Similar Articles | Additional Information

Abstract: Second-order accurate approximations to the curvature function along a sufficiently smooth plane curve are presented, the curve being given in finite form (and thus, approximately) by points taken along its full length. The curvature estimates are continuous and invariant under translation and rotation, and they are based on local information--so are easy to implement computationally. In particular, second-order accurate estimates of surface tension forces halfway between immediate neighbors in the curve's mesh can thereby be made for hydrodynamic simulations.

The construction makes use of any of the common techniques one might contemplate for using the information present in three adjacent points (of the points) in order to estimate the curve's curvature near those three points. It may do this because each of these techniques yields a number which is, to within second order in the distances between the three points, the value of the true curvature function at the same place, namely, at the arithmetic mean of the location of the three points as measured along the curve. The asymptotic form, displaying all terms through the second order, of error estimates for these techniques is provided, along with comparison of gross properties and numerical examples. Finally, continuous, locally second-order accurate, global approximation to the curvature function is obtained by interpolation of successive local estimates between the locations of successive means.

A related result is given for the simpler but analogous situation concerning the *n*th-order difference quotient of a function of one variable. The broken line interpolant of successive *n*th difference quotients, between the successive mean values of their stencil points, provides a continuous, locally second-order accurate, global approximation to the *n*th derivative. It also coincides, between two successive stencil means, with the *n*th derivative of the polynomial interpolant of the data points associated with the two successive stencils.

**[1]**J. D. Burns,*Joining Arbitrary Curves by Segments of Cornu Spirals*, Tech Memo #L-157, EG & G Inc., 1966, 21pp.**[2]**J. C. Ferguson,*Shape Preserving Parametric Cubic Curve Interpolation*, Ph.D. Thesis, University of New Mexico, Albuquerque, 1984, 190pp.**[3]**H.-O. Kreiss, T. A. Manteuffel, B. Swartz, B. Wendroff, and A. B. White Jr.,*Supra-convergent schemes on irregular grids*, Math. Comp.**47**(1986), no. 176, 537–554. MR**856701**, 10.1090/S0025-5718-1986-0856701-5**[4]**R. J. Y. McLeod & P. H. Todd, "Intrinsic grometry and curvature estimation from noisy data," draft preprint, 1985.**[5]**A. W. Nutbourne, P. M. McLellan & R. M. L. Kensit, "Curvature profiles for plane curves,"*Comput.-Aided Des.*, v. 7, 1972, pp. 176-184.**[6]**T. K. Pal, "Intrinsic spline curve with local control,"*Comput.-Aided Des.*, v. 10, 1977, pp. 19-29.**[7]**A. Schechter, "Linear blending of curvature profiles,"*Comput.-Aided Des.*, v. 10, 1978, pp. 101-109.**[8]**Dirk J. Struik,*Lectures on Classical Differential Geometry*, Addison-Wesley Press, Inc., Cambridge, Mass., 1950. MR**0036551**

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Additional Information

DOI:
http://dx.doi.org/10.1090/S0025-5718-1987-0890263-2

Keywords:
Curvature approximation,
difference quotient,
divided difference,
irregular grid

Article copyright:
© Copyright 1987
American Mathematical Society