Showing posts with label Supreme Leader. Show all posts
Showing posts with label Supreme Leader. Show all posts

Monday, 11 April 2016

Computational Geometry, C++ and Wykobi

A brief introduction in computational geometry algorithms using Wykobi and C++
Wykobi Polygon Clipping - Copyright Arash Partow

Introduction

Good C++ computational geometry libraries to date have been hideously over-designed and incorporate usage patterns that in most cases require extensive redesigns and rewrites of code in order to functionally integrate within an existing project.

Sometimes a lightweight portable solution that has a bit of error is deemed to be more appropriate and reasonable. However these libraries even though being more than able to cater for such a requirement still burden the end user with undue code clutter, very steep learning curves and in some cases unnecessary overheads.

The solution to such a situation is to simplify use, implementation and application. This can be achieved by reducing the number of contact points between the computational geometry back-end and the developer-application combo. But at the same time giving full control of the computations and ensuing folding processes to the user to the extent where the user can decide between using a general solution for a particular problem or a more specialized solution.

For example, say you have two line segments and you want to know if they are intersecting, one could use a general solution, but say if you had prior knowledge that the line segments were either always going to be vertical or horizontal, this would allow one to use a more efficient method to obtain the same result. Typically (but not always) a generalized result is less efficient than a specialised result for the specialised case - by virtue of the fact that the generalised result has to take into account the 1001 other possible scenarios.

A possible solution to the above mentioned problem is Wykobi. Wykobi is an efficient, robust and simple to use multi-platform 2D/3D computational geometry library. Wykobi provides a concise, predictable, and deterministic interface for geometric primitives and complex geometric routines using and conforming to the ISO/IEC 14882:2003 C++ language specification.

The design and structure of Wykobi lends itself to easy and seamless integration into projects of any scale that require a robust yet efficient 2D/3D computational geometry back-end.

Wykobi as a library can be used to efficiently and seamlessly solve complex geometric problems such as collision and proximity detection, efficient spatial queries and geometric constructions used in areas as diverse as gaming, computer aided design and manufacture, electronic design and geographic information systems - just to name a few.

Wykobi provides a series of primitive geometric structures for use within the various algorithms of interest such as intersections, distances, inclusions and clipping operations.

An assessment of recent Iranian fertility trends using parity progression ratios

Abstract

Background: In 2013 a draft population bill was introduced in the Iranian Parliament. Based on the presumption that fertility in Iran had fallen to a very low level, the bill proposed a wide range of pronatalist policies with the aim of increasing fertility to 2.5 births per woman. The draft law called for restrictions on the employment of women and young single people and inducements for women to marry in their late teens. New estimates of fertility, such as those provided in this paper, cast doubt upon the view that fertility had fallen to a very low level. In May 2014 a statement issued by the Supreme Leader provided guidelines for a more moderate approach to sustaining fertility at around the replacement level.

Objective: To measure the trend in fertility in Iran, especially from 2000 onwards.
Methods: Using the 2010 IDHS, the synthetic cohort parity progression ratio method is used to measure the fertility trend in Iran. Synthetic parity progressions are compared with real cohort parity progressions to examine the presence of tempo effects. Comparison is made with age-based measures from surveys, censuses, and the birth registration system.
Results: This paper demonstrates that fertility in Iran was constant for the decade 2000-2009, at a level of around 1.8-2.0 births per woman.
Conclusions: Our findings provide evidence supporting a more moderate approach to sustaining fertility in Iran at around the replacement level.
Comments: The paper demonstrates the advantages of parity-based measurement over age-based measurement when tempo effects may be involved.

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