心脏线 meaning in English

cardioid
epicycloid

What does the cardioid envelope
心脏线的包络为何
For the cardioid curve , a fast pixel - level drawing algorithm is presented
摘要给出了快速绘制心脏线的逐点算法。
On each step of iteration , no trigonometric function is used , and only four multiplications for cardioid curve are required
迭代过程中避免了三角函数的运算，每步仅需4次（心脏线）乘法运算。
By taking advantage of the characteristic of the curves ' expression , the algorithm changes the cardioid curve into the linearly combination of some simple iterations
基于曲线表达式的特点，该算法将心脏线的点坐标迭代关系转化为几个简单的迭代关系的线性组合。
They not only inherit the advantages of bezier curves and b - spline curves , also can be used to represent straight lines precisely and some remarkable transcendental curves precisely , such as circular arc , ellipse , cardioids and twisted pair line etc . especially , the uniform t - b - spline curve of three degrees is smoother than b - spline curve and c - b - spline curve of the same order
此外由于它们还具有三角函数的优点，故既可以精确表示直线段、二次多项式曲线段又可以精确表示圆弧、椭圆弧等二次曲线以及心脏线、双纽线等超越曲线。特别地， 3次均匀t - b样条曲线曲面比同阶均匀b样条( c - b样条)曲线曲面具有更高的光滑度。