Dear CP,
Thank you for your help. But when I try to evaluate the X-function I allways get an error message:
"interp1xy:X-Function failed to execute!
Internal error code: -898, -45"
The code I use is basically the following:
// define xf
					string XF_Name = "interp1xy";
					XFBase xf(XF_Name);
					if(!xf)
					{
						out_str("Fehler beim Interpolieren des Skalierungsfaktors");
						return;
					};
					
					...
					
					// create datasets and fill with result vectors
					Dataset temp_x_1(wks_SkF_1D, 0);
					Dataset temp_y_1(wks_SkF_1D, 1);
					
					temp_x_1 = v_Scaling_Factor;
					temp_y_1 = v_Sum_Residues;
					
					// create DataRange for xf
					DataRange dr_in;
					DataRange dr_out;
					
					// fill DataRange
					dr_in.Add(wks_SkF_1D, 0, "X");
					dr_in.Add(wks_SkF_1D, 1, "Y");
					
					
					dr_out.Add(wks_SkF_1D, 2, "X");
					dr_out.Add(wks_SkF_1D, 3, "Y");
					
					// define xf arguments Max and Min
					double xf_X_min = 0.00;
					double xf_X_max = 1.20;
					
					// number of interpolated points  
					int xf_X_points = 1200;
					
					if( !xf.IsValid() )
   					{
        				out_str("Fehler beim Interpolieren des Skalierungsfaktors");
        				return;
    				}    
										
					// set xf arguments
					if(
						!xf.SetArg(1, dr_in) || 
						!xf.SetArg(8, dr_out) ||
						!xf.SetArg(2, 2) ||
						!xf.SetArg(3, xf_X_points) ||
						!xf.SetArg(4, xf_X_min) ||
						!xf.SetArg(5, xf_X_max))
						{
							out_str("Fehler beim Interpolieren des Skalierungsfaktors");
							return;
						}
								
					// evaluate xf
					if (!xf.Evaluate())
					{
						out_str("Fehler beim Interpolieren des Skalierungsfaktors");
						return;
					}
					
The error occurs in debug mode in the line where I evaluate the x-function. Could you please tell me what the error codes mean and what is wrong with my code?
P.S. At the moment I have only access to Origin 8.0 SR2.