快速斜边算法嵌入式处理器？ [英] Fast Hypotenuse Algorithm for Embedded Processor?

问题描述

是否有确定的角度的斜边一个聪明/高效的算法（即的sqrt（A²+称b²）），使用无硬件的嵌入式处理器上定点数学乘？

Is there a clever/efficient algorithm for determining the hypotenuse of an angle (i.e. sqrt(a² + b²)), using fixed point math on an embedded processor without hardware multiply?

推荐答案

除非你这样做是在> 1kHz时，在MCU甚至成倍没有硬件 MUL ISN Ť可怕。更糟糕的是多少开方。我会尝试修改我的应用程序，因此并不需要在所有的计算。

Unless you're doing this at >1kHz, multiply even on a MCU without hardware MUL isn't terrible. What's much worse is the sqrt. I would try to modify my application so it doesn't need to calculate it at all.

标准库很可能是最好的，如果你真的需要它，但你可以看看使用牛顿方法作为可能的选择。这将需要数乘法/除法周期不过来执行。

Standard libraries would probably be best if you actually need it, but you could look at using Newton's method as a possible alternative. It would require several multiply/divide cycles to perform, however.

• 爱特梅尔应用笔记AVR200：乘，除法例程（PDF）


• 这开方对AVR单片机的论坛功能


• 另一个 AVR怪胎发布

• Atmel App note AVR200: Multiply and Divide Routines (pdf)
• This sqrt function on AVR Freaks forum
• Another AVR Freaks post

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