在C#中的数学优化 [英] Math optimization in C#
问题描述
我已经整天在分析应用程序,并经优化code的一对夫妇的位,我离开了这个我的待办事项清单上。它是一个神经网络,被调用超过100万次的激活功能。根据dotTrace,它相当于整体功能的时间约60%。
你会如何优化呢?
公共静态浮动乙状结肠(double值){
回报(浮)(1.0 /(1.0 + Math.Pow(Math.E,-value)));
}
尝试:
公共静态浮动乙状结肠(double值){
返回1.0F /(1.0F +(浮点)Math.Exp( - 值));
}
编辑:我做了快速基准。在我的机器,上面code是比你的方法快43%左右,这在数学上等价code是teeniest有点快(比原来快46%):
公共静态浮动乙状结肠(double值){
浮K = Math.Exp(值);
返回K /(1.0F + K);
}
编辑2:我不知道开销C#功能有多少,但如果你的#include<文件math.h>
中源$ C $ C,你应该能够利用这一点,它采用了浮动EXP函数。这可能是一个快一点。
公共静态浮动乙状结肠(double值){
浮K = expf((浮点)值);
返回K /(1.0F + K);
}
此外,如果你正在做的数以百万计的电话,该函数调用的开销可能是一个问题。试着做一个内联函数,看看如果这是任何帮助。
I've been profiling an application all day long and, having optimized a couple bits of code, I'm left with this on my todo list. It's the activation function for a neural network, which gets called over a 100 million times. According to dotTrace, it amounts to about 60% of the overall function time.
How would you optimize this?
public static float Sigmoid(double value) {
return (float) (1.0 / (1.0 + Math.Pow(Math.E, -value)));
}
Try:
public static float Sigmoid(double value) {
return 1.0f / (1.0f + (float) Math.Exp(-value));
}
EDIT: I did a quick benchmark. On my machine, the above code is about 43% faster than your method, and this mathematically-equivalent code is the teeniest bit faster (46% faster than the original):
public static float Sigmoid(double value) {
float k = Math.Exp(value);
return k / (1.0f + k);
}
EDIT 2: I'm not sure how much overhead C# functions have, but if you #include <math.h>
in your source code, you should be able to use this, which uses a float-exp function. It might be a little faster.
public static float Sigmoid(double value) {
float k = expf((float) value);
return k / (1.0f + k);
}
Also if you're doing millions of calls, the function-calling overhead might be a problem. Try making an inline function and see if that's any help.
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