Cos(90)返回非常接近0的值，但是我需要0? [英] Cos(90) returning a value very close to 0, but I need 0?

问题描述

temp_x_btm_left的值= 0&temp_y_btm_left = 1;

The values for temp_x_btm_left = 0 & temp_y_btm_left=1;

angle = 90;

//Moving the bottom left coordinates
_btm_left.real() = (temp_x_btm_left * cos(angle*PI/180)) 
                   - (temp_y_btm_left * sin(angle*PI/180));
_btm_left.imag() = (temp_x_btm_left * sin(angle*PI/180)) 
                   + (temp_y_btm_left * cos(angle*PI/180));

该代码应该将对象逆时针旋转90度，但 _btm_left.imag()返回的值实际上接近0 = 1.437949e-009，而我确实需要它是0.

The code is supposed to rotate the object 90 degrees counter-clockwise, which it does but the _btm_left.imag() returns a value really close to 0 = 1.437949e-009, and I really need it being 0.

我已经尝试过 setprecision()和 setw()，但这似乎没有任何效果.有什么方法可以解决此类问题吗?还是需要创建自己的方法来解决此问题?！

I've tried setprecision() and setw() but it doesn't seem to have any effect. Are there any methods for anything like this or do I need to create my own to solve this?!

推荐答案

只要| v1-v2 |<预定义的Delta，只需考虑v1 == v2.

As long as |v1-v2| < predefinedDelta, simply consider v1 == v2.

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