Diff: IIR_filter.cpp

Revision:

12:6287235b2570

Parent:

10:a28f393c6716

Child:

13:a308f5e6c306

--- a/IIR_filter.cpp	Wed Apr 04 17:20:55 2018 +0000
+++ b/IIR_filter.cpp	Thu Apr 05 08:28:32 2018 +0000
@@ -20,20 +20,20 @@
     na = 1; // Filter Order
     
     // filter coefficients
-    B = (float*)malloc((nb+1)*sizeof(float));
-    A = (float*)malloc(na*sizeof(float));    
-    B[0] = 2.0f/(2.0f*T + Ts);
+    B = (double*)malloc((nb+1)*sizeof(double));
+    A = (double*)malloc(na*sizeof(double));    
+    B[0] = 2.0/(2.0*(double)T + (double)Ts);
     B[1] = -B[0];
-    A[0] = -(2.0f*T - Ts)/(2.0f*T + Ts);
+    A[0] = -(2.0*(double)T - (double)Ts)/(2.0*(double)T + (double)Ts);
     
     // signal arrays
-    uk = (float*)malloc((nb+1)*sizeof(float));
-    yk = (float*)malloc(na*sizeof(float));
-    uk[0]= uk[1] = 0.0f;
-    yk[0] = 0.0f;
+    uk = (double*)malloc((nb+1)*sizeof(double));
+    yk = (double*)malloc(na*sizeof(double));
+    uk[0]= uk[1] = 0.0;
+    yk[0] = 0.0;
     
     // dc-gain
-    this->K = 0.0f;
+    this->K = 0.0;
 }
 
 // G(s) = K/(T*s + 1)
@@ -44,20 +44,20 @@
     na = 1; // Filter Order
     
     // filter coefficients
-    B = (float*)malloc((nb+1)*sizeof(float));
-    A = (float*)malloc(na*sizeof(float));      
-    B[0] = Ts/(Ts + 2.0f*T);
+    B = (double*)malloc((nb+1)*sizeof(double));
+    A = (double*)malloc(na*sizeof(double));      
+    B[0] = (double)Ts/((double)Ts + 2.0*(double)T);
     B[1] = B[0];
-    A[0] = (Ts - 2.0f*T)/(Ts + 2.0f*T); 
+    A[0] = ((double)Ts - 2.0*(double)T)/((double)Ts + 2.0*(double)T); 
     
     // signal arrays
-    uk = (float*)malloc((nb+1)*sizeof(float));
-    yk = (float*)malloc(na*sizeof(float));
-    uk[0]= uk[1] = 0.0f;
-    yk[0] = 0.0f;
+    uk = (double*)malloc((nb+1)*sizeof(double));
+    yk = (double*)malloc(na*sizeof(double));
+    uk[0]= uk[1] = 0.0;
+    yk[0] = 0.0;
     
     // dc-gain
-    this->K = K;
+    this->K = (double)K;
 }
 
 // G(s) = K*w0^2/(s^2 + 2*D*w0*s + w0^2) 
@@ -68,25 +68,25 @@
     na = 2; // Filter Order
     
     // filter coefficients
-    B = (float*)malloc((nb+1)*sizeof(float));
-    A = (float*)malloc(na*sizeof(float));
-    float k0 = Ts*Ts*w0*w0;
-    float k1 = 4.0f*D*Ts*w0;
-    float k2 = k0 + k1 + 4.0f;    
-    B[0] = K*k0/k2;
-    B[1] = 2.0f*B[0];
+    B = (double*)malloc((nb+1)*sizeof(double));
+    A = (double*)malloc(na*sizeof(double));
+    double k0 = (double)Ts*(double)Ts*(double)w0*(double)w0;
+    double k1 = 4.0*(double)D*(double)Ts*(double)w0;
+    double k2 = k0 + k1 + 4.0;    
+    B[0] = (double)K*k0/k2;
+    B[1] = 2.0*B[0];
     B[2] = B[0]; 
-    A[0] = (2.0f*k0 - 8.0f)/k2;
-    A[1] = (k0 - k1 + 4.0f)/k2;
+    A[0] = (2.0*k0 - 8.0)/k2;
+    A[1] = (k0 - k1 + 4.0)/k2;
     
     // signal arrays
-    uk = (float*)malloc((nb+1)*sizeof(float));
-    yk = (float*)malloc(na*sizeof(float));
-    uk[0]= uk[1] = uk[2] = 0.0f;
-    yk[0] = yk[1] = 0.0f;
+    uk = (double*)malloc((nb+1)*sizeof(double));
+    yk = (double*)malloc(na*sizeof(double));
+    uk[0]= uk[1] = uk[2] = 0.0;
+    yk[0] = yk[1] = 0.0;
     
     // dc-gain
-    this->K = K;
+    this->K = (double)K;
 }
 
 IIR_filter::IIR_filter(float *b,float *a,int nb_, int na_){
@@ -96,22 +96,22 @@
     this->na = na_;      // Filter Order
     
     // filter coefficients
-    B = (float*)malloc((nb+1)*sizeof(float));
-    A = (float*)malloc(na*sizeof(float));
-    uk = (float*)malloc((nb+1)*sizeof(float));
-    yk = (float*)malloc(na*sizeof(float));
+    B = (double*)malloc((nb+1)*sizeof(double));
+    A = (double*)malloc(na*sizeof(double));
+    uk = (double*)malloc((nb+1)*sizeof(double));
+    yk = (double*)malloc(na*sizeof(double));
     
     for(int k=0;k<=nb;k++){
         B[k]=b[k];
-        uk[k]=0.0f;
+        uk[k]=0.0;
         }
     for(int k=0;k<na;k++){
         A[k] = a[k];
-        yk[k] = 0.0f;
+        yk[k] = 0.0;
         }
     
     // dc-gain
-    this->K = 1.0f;
+    this->K = 1.0;
 }
 
     
@@ -119,9 +119,9 @@
     
 void IIR_filter::reset(float val) {
     for(int k=0;k < nb;k++)
-        uk[k] = val;
+        uk[k] = (double)val;
     for(int k=0;k < na;k++)
-        yk[k] = val*K;
+        yk[k] = (double)val*K;
         
 }
 
@@ -131,11 +131,11 @@
     y(n) =  B[0]*u(k)   + B[1]*u(k-1) + ... + B[nb]*u(k-nb) + ...
           - A[0]*y(k-1) - A[1]*y(k-2) - ... - A[na]*y(n-na)
 */
-float IIR_filter::filter(float input){
+float IIR_filter::filter(double input){
     for(int k = nb;k > 0;k--)    // shift input values back
         uk[k] = uk[k-1];
     uk[0] = input;
-    float ret = 0.0f;
+    double ret = 0.0;
     for(int k = 0;k <= nb;k++)
         ret += B[k] * uk[k];
     for(int k = 0;k < na;k++)
@@ -143,5 +143,5 @@
     for(int k = na;k > 1;k--)
         yk[k-1] = yk[k-2];
     yk[0] = ret;
-    return ret;
+    return (float)ret;
 }