Added frft functions towards codegen (c code on PS)

frft_codegen/bizinter.m

@@ -0,0 +1,37 @@
+function xint=bizinter(x)
+
+N=length(x);
+im = 0;
+if sum(abs(imag(x)))>0
+  im = 1;
+  imx = imag(x);
+  x  = real(x);
+end
+
+x2=x(:);
+x2=[x2.'; zeros(1,N)];
+x2=x2(:);
+xf=fft(x2);
+if rem(N,2)==1      %N = odd
+	N1=fix(N/2+1); N2=2*N-fix(N/2)+1;
+	xint=2*real(ifft([xf(1:N1); zeros(N,1)  ;xf(N2:2*N)].'));
+else
+	xint=2*real(ifft([xf(1:N/2); zeros(N,1)  ;xf(2*N-N/2+1:2*N)].'));
+end
+if ( im == 1)
+ x2=imx(:);
+ x2=[x2.'; zeros(1,N)];
+ x2=x2(:);
+ xf=fft(x2);
+ if rem(N,2)==1      %N = odd
+	N1=fix(N/2+1); N2=2*N-fix(N/2)+1;
+	xmint=2*real(ifft([xf(1:N1); zeros(N,1)  ;xf(N2:2*N)].'));
+ else
+	xmint=2*real(ifft([xf(1:N/2); zeros(N,1)  ;xf(2*N-N/2+1:2*N)].'));
+ end
+ xint = xint + 1j*xmint;
+end
+
+xint = xint(:);
+
+end