SigmaStudio的帮助文档里有写到General 1st-Order Filters  Highpass 的系数计算公式为：
ω0 = 2*pi*f0/Fs
gainLinear = 10^(gain/20)
a1 = 2.7^-ω0
b0 = gainLinear * a1
b1 = -a1 * gainLinear
我用C按照上面的方法写了段计算程序，但结果却与SigmaStudio软件的计算结果不同，请帮我看看是哪里出错了？谢谢！

////(f0=1000,gain=0,fs=48000)：

float omega,A;      
omega=(float)(2*3.1415926535897932384626433832795*1000/48000);
A=pow(10,(0/20));                      
a1=pow(2.7,-omega);
b0=A*a1;
b1=-a1*A;
a1=-a1;

程序运行结果：
b0=0.878081
b1=-0.878081
a1=0.878081

SigmaStudio软件计算结果(f0=1000,gain=0,fs=48000)：
Param Name:  FistOrderSingle101
Param Value:  0.939040541648865

Param Name:  FistOrderSingle111
Param Value:  -0.939040541648865

Param Name:  FistOrderSingle121
Param Value:  0.878081083297729

两个结果不同，请帮忙，谢谢！

程序：

   omega=(float)(2*M_PI*fc/Fs);              

   A=pow(10,(G/20));

   alpha=sin(omega)/(2*Q);

   a0=1+alpha/A;

   a1=-2*cos(omega);

   a2=1-alpha/A;

   b0=(1+alpha*A);//*gainLinear;

   b1=-(2*cos(omega));//*gainLinear;

   b2=(1-alpha*A);//*gainLinear;

   b0=b0/a0;

   b1=b1/a0;

    b2=b2/a0;

    a1=a1/a0;

    a2=a2/a0;

请也帮忙看看，谢谢！

我照文档写了General 1st-Order Filters  Low pass 是正确的，换成HIGH PASS的公式就不对了。

        double f0 = 1000;

        double fs = 48000;

        double gain = 0;

//HP

            double omega = 2d * Math.PI * f0 / fs;

            double gainLinear = Math.Pow(10d, gain / 20d);

            double a1 = Math.Pow(2.7, - omega);

            //double b0 = gainLinear * a1;

            //double b1 = -a1 * gainLinear;

            double b1 = -1.0 * (1.0 + a1) * 0.5 * gainLinear;

            double b0 = -b1;

http://wiki.analog.com/resources/tools-software/sigmastudio/toolbox/filters