Adapted the old example of helical forcing with profiles to conform with the revised syntax

acc/mhd_solver/pcstyleforcing.h

@@ -0,0 +1,55 @@
+// PC-style helical forcing with profiles
+uniform Vector AC_kk;
+uniform Vector AC_coef1;
+uniform Vector AC_coef2;
+uniform Vector AC_coef3;
+uniform Vector AC_fda;
+
+uniform Scalar AC_phase;
+uniform Scalar AC_fact;
+uniform Scalar AC_k1_ff;
+
+uniform ScalarArray AC_profx;
+uniform ScalarArray AC_profy;
+uniform ScalarArray AC_profz;
+uniform ScalarArray AC_profx_hel;
+uniform ScalarArray AC_profy_hel;
+uniform ScalarArray AC_profz_hel;
+
+uniform int AC_iforcing_zsym;
+
+// PC-style helical forcing with support for profiles
+Vector
+pcforcing(int3 vertexIdx, int3 globalVertexIdx, Scalar dt, ScalarArray profx, ScalarArray profy,
+          ScalarArray profz, ScalarArray profx_hel, ScalarArray profy_hel, ScalarArray profz_hel)
+{
+    Vector pos = (Vector){(globalVertexIdx.x - AC_nx_min) * AC_dsx,
+                          (globalVertexIdx.y - AC_ny_min) * AC_dsy,
+                          (globalVertexIdx.z - AC_nz_min) * AC_dsz};
+
+    Complex fx = AC_fact * exp(Complex(0, AC_kk.x * AC_k1_ff * pos.z + AC_phase));
+    Complex fy = exp(Complex(0, AC_kk.y * AC_k1_ff * pos.y));
+
+    Complex fz;
+    if (AC_iforcing_zsym == 0) {
+        fz = exp(Complex(0.0, AC_kk.z * AC_k1_ff * pos.z));
+    }
+    else if (AC_iforcing_zsym == 1) {
+        fz = Complex(cos(AC_kk.z * AC_k1_ff * pos.z), 0);
+    }
+    else if (AC_iforcing_zsym == -1) {
+        fz = Complex(sin(AC_kk.z * AC_k1_ff * pos.z), 0);
+    }
+    else {
+        // Failure
+    }
+
+    Complex fxyz = fx * fy * fz;
+
+    // TODO recheck indices
+    Scalar force_ampl    = profx[vertexIdx.x - NGHOST] * profy[vertexIdx.y] * profz[vertexIdx.z];
+    Scalar prof_hel_ampl = profx_hel[vertexIdx.x - NGHOST] * profy_hel[vertexIdx.y] *
+                           profz_hel[vertexIdx.z];
+
+    return force_ampl * AC_fda * (Complex(AC_coef1.x, prof_hel_ampl * AC_coef2.x) * fxyz).x;
+}