diff --git a/N803_model_2.m b/N803_model_2.m
index 43ccc5d..6f5d544 100644
--- a/N803_model_2.m
+++ b/N803_model_2.m
@@ -1,7 +1,7 @@
 %% N803_model_2.m - solves ODE model for N-803 treatment of SIV
 %
 %     /--------------------------------------------------------------\
-%     | Date:         06/27/2022                                     |
+%     | Date:         06/29/2022                                     |
 %     | Author:       Jonathan Cody                                  |
 %     | Affiliation:  Purdue University                              |
 %     |               Weldon School of Biomedical Engineering        |
@@ -35,8 +35,8 @@
 %	OPTIONS
 %  ========================================================================
 %
-% varargin = cell vector used to add optional inputs (see line 54)
-% EX: N803_model_2(SoluTimes,DoseTimes,Pars,Yic,'InputName',[InputValue])
+% Opts = cell vector used to add optional inputs (see list on line 54)
+% EX: Opts = {'AbsTol',1e-2} will set ode solver absolute tolerance to 1e-2
 %
 %% ========================================================================
 %	OUTPUTS
@@ -48,7 +48,7 @@
 %% ========================================================================
 %	FUNCTION
 %  ========================================================================
-function Y_OUT = N803_model_2(SoluTimes,DoseTimes,Pars,Yic,varargin)
+function Y_OUT = N803_model_2(SoluTimes,DoseTimes,Pars,Yic,Opts)
 
 % Declare optional input default values
 EqualPars = []     ;% vector of indices in 'Pars' for equating parameters
@@ -62,14 +62,14 @@
 odeSolver = '15s'  ;% ode solver function: 'ode15s' or 'ode23s'
 
 % Overwrite optional inputs, if specified
-for n = 1:length(varargin)
-if strcmp('EqualPars', varargin(n))  ; EqualPars = varargin{n+1}  ; end
-if strcmp('fullOut',   varargin(n))  ; fullOut   = varargin{n+1}  ; end
-if strcmp('timeOut',   varargin(n))  ; timeOut   = varargin{n+1}  ; end
-if strcmp('warnOff',   varargin(n))  ; warnOff   = varargin{n+1}  ; end
-if strcmp('AbsTol',    varargin(n))  ; AbsTol    = varargin{n+1}  ; end
-if strcmp('RelTol',    varargin(n))  ; RelTol    = varargin{n+1}  ; end
-if strcmp('odeSolver', varargin(n))  ; odeSolver = varargin{n+1}  ; end
+for n = 1:length(Opts)
+if strcmp('EqualPars', Opts(n))  ; EqualPars = Opts{n+1}  ; end
+if strcmp('fullOut',   Opts(n))  ; fullOut   = Opts{n+1}  ; end
+if strcmp('timeOut',   Opts(n))  ; timeOut   = Opts{n+1}  ; end
+if strcmp('warnOff',   Opts(n))  ; warnOff   = Opts{n+1}  ; end
+if strcmp('AbsTol',    Opts(n))  ; AbsTol    = Opts{n+1}  ; end
+if strcmp('RelTol',    Opts(n))  ; RelTol    = Opts{n+1}  ; end
+if strcmp('odeSolver', Opts(n))  ; odeSolver = Opts{n+1}  ; end
 end
 
 % check inputs vector orientation
@@ -324,8 +324,8 @@
     J(03,17   ) = daEdR * E0 ;
     
     % Partial derivatives of f4-10 = dE2-8/dt
-    J(39:19:153) = - dA - pE ;
-    J(40:19:154) = 2*pE ;
+    J(37:18:145) = - dA - pE ;
+    J(38:18:146) = 2*pE ;
     J(10,10) = - dA - mE ;
     
     % Partial derivatives of f11 = dB0/dt