Fitting logarithmic b ln(c+x), a+bln(c+x) or reciprocal b/(c+x), a+b/(c+x) regression models to data by the least squares method asks for the determination of the closure of the set of each type of these functions def...Fitting logarithmic b ln(c+x), a+bln(c+x) or reciprocal b/(c+x), a+b/(c+x) regression models to data by the least squares method asks for the determination of the closure of the set of each type of these functions defined on a finite domain. It follows that a minimal solution may not exist. But it does exist when the closure is considered.展开更多
针对经典自然对数坐标旋转数字计算机(coordinate rotation digital computer,CORDIC)算法在应用上存在问题,研究扩展收敛域任意对数CORDIC算法与FPGA实现。通过区间压缩方法,对收敛域外的数据进行转换,实现收敛域扩展至全收敛域,并应...针对经典自然对数坐标旋转数字计算机(coordinate rotation digital computer,CORDIC)算法在应用上存在问题,研究扩展收敛域任意对数CORDIC算法与FPGA实现。通过区间压缩方法,对收敛域外的数据进行转换,实现收敛域扩展至全收敛域,并应用换底公式扩展到任意底数的对数运算。仿真试验表明,采用15级流水线结构,以10为底的对数CORDIC运算最大时延小于17个时钟周期,最大计算误差为0.000 27。该算法应用于40 mm玻璃钢的超声检测中,其TCG回波图能有效抑制杂散波,提高信号的分辨力,运算速度比传统方法快,对超声相控仪器的开发具有应用价值。展开更多
文摘Fitting logarithmic b ln(c+x), a+bln(c+x) or reciprocal b/(c+x), a+b/(c+x) regression models to data by the least squares method asks for the determination of the closure of the set of each type of these functions defined on a finite domain. It follows that a minimal solution may not exist. But it does exist when the closure is considered.
