六边形蜂窝网格，计算出半径从3到20的所需圆形中继站数量的最小值。-Hexagonal honeycomb grid to calculate the radius of from 3 to 20 round relay station number of the minimum required.

求解六边形幻方的c程序！！有人用52年才算出来的，计算机几秒搞定。-Solving hexagonal magic square c program!

Titanium alloys have excellent properties for theirtarget applications however their use is still limited by high price and formability issues. To avoid extensive on-site trials and to cut development costs, a numerical simulation method is dev