diff --git a/models/trig/trig.dat b/models/trig/trig.dat
new file mode 100644
index 00000000..2bf025e3
--- /dev/null
+++ b/models/trig/trig.dat
@@ -0,0 +1,41 @@
+ARCCOS calculation
+0	1
+1	1
+2	1
+3	1
+ARCSIN calculation
+0	1
+1	1
+2	1
+3	1
+ARCTAN calculation
+0	1
+1	1
+2	1
+3	1
+COS calculation
+0	0.540302
+1	0.540302
+2	0.540302
+3	0.540302
+FINAL TIME
+0	3
+INITIAL TIME
+0	0
+SAVEPER
+0	1
+1	1
+2	1
+3	1
+SIN calculation
+0	0.841471
+1	0.841471
+2	0.841471
+3	0.841471
+TAN calculation
+0	1.55741
+1	1.55741
+2	1.55741
+3	1.55741
+TIME STEP
+0	1
diff --git a/models/trig/trig.mdl b/models/trig/trig.mdl
new file mode 100644
index 00000000..6a7c27df
--- /dev/null
+++ b/models/trig/trig.mdl
@@ -0,0 +1,127 @@
+{UTF-8}
+ARCCOS calculation=
+	ARCCOS( 0.540302 )
+	~	dmnl
+	~		~	:SUPPLEMENTARY 
+	|
+
+ARCSIN calculation=
+	ARCSIN( 0.841471 )
+	~	dmnl
+	~		~	:SUPPLEMENTARY 
+	|
+
+ARCTAN calculation=
+	ARCTAN( 1.55741 )
+	~	dmnl
+	~		~	:SUPPLEMENTARY 
+	|
+
+COS calculation=
+	COS(1)
+	~	dmnl
+	~	Input is in radians from 0 to 2pi.
+	~	:SUPPLEMENTARY 
+	|
+
+SIN calculation=
+	SIN( 1 )
+	~	dmnl
+	~	Input is in radians from 0 to 2pi.
+	~	:SUPPLEMENTARY 
+	|
+
+TAN calculation=
+	TAN( 1 )
+	~	dmnl
+	~	Input is in radians from 0 to 2pi.
+	~	:SUPPLEMENTARY 
+	|
+
+********************************************************
+	.Control
+********************************************************~
+		Simulation Control Parameters
+	|
+
+FINAL TIME  = 3
+	~	Month
+	~	The final time for the simulation.
+	|
+
+INITIAL TIME  = 0
+	~	Month
+	~	The initial time for the simulation.
+	|
+
+SAVEPER  = 
+        TIME STEP 
+	~	Month [0,?]
+	~	The frequency with which output is stored.
+	|
+
+TIME STEP  = 1
+	~	Month [0,?]
+	~	The time step for the simulation.
+	|
+
+\\\---/// Sketch information - do not modify anything except names
+V300  Do not put anything below this section - it will be ignored
+*View 1
+$-1--1--1,0,|12||-1--1--1|-1--1--1|-1--1--1|-1--1--1|-1--1--1|96,96,100,0
+10,1,ARCSIN calculation,683,171,56,22,8,3,0,0,-1,0,0,0,0,0,0,0,0,0
+10,2,TAN calculation,283,432,47,22,8,3,0,0,-1,0,0,0,0,0,0,0,0,0
+10,3,SIN calculation,290,182,44,22,8,3,0,0,-1,0,0,0,0,0,0,0,0,0
+10,4,COS calculation,298,316,47,22,8,3,0,0,-1,0,0,0,0,0,0,0,0,0
+10,5,ARCCOS calculation,674,307,59,22,8,3,0,0,-1,0,0,0,0,0,0,0,0,0
+10,6,ARCTAN calculation,685,437,59,22,8,3,0,0,-1,0,0,0,0,0,0,0,0,0
+12,7,0,1104,304,250,166,8,15,0,0,1,0,0,0,0,0,0,0,0,0
+Table_of_Output
+///---\\\
+:TABLE Table_of_Output
+:TITLE Table of Output
+:PRETTYNUM
+:VAR ARCCOS calculation
+:DATASET *1
+:VAR ARCSIN calculation
+:DATASET *1
+:VAR ARCTAN calculation
+:DATASET *1
+:VAR COS calculation
+:DATASET *1
+:VAR SIN calculation
+:DATASET *1
+:VAR TAN calculation
+:DATASET *1
+:L<%^E!@
+1:current.vdfx
+4:Time
+5:TAN calculation
+9:current
+19:100,0
+24:0
+25:3
+26:3
+15:0,0,0,0,0,0
+27:0,
+34:0,
+42:0
+72:0
+73:0
+95:0
+96:0
+97:0
+77:0
+78:0
+102:1
+93:0
+94:0
+92:0
+91:0
+90:0
+87:0
+75:
+43:
+103:8,8,8,3,8
+105:0,0,0,0,0,0,0,0,0,0
+104:Lucida Grande|12||0-0-0|0-0-0|-1--1--1|0-0-255|192-192-192|-1--1--1
diff --git a/packages/cli/src/c/vensim.h b/packages/cli/src/c/vensim.h
index 1d1b0061..51e4e268 100644
--- a/packages/cli/src/c/vensim.h
+++ b/packages/cli/src/c/vensim.h
@@ -16,6 +16,9 @@ extern "C" {
 // https://www.vensim.com/documentation/22300.html
 //
 #define _ABS(x) fabs(x)
+#define _ARCCOS(x) acos(x)
+#define _ARCSIN(x) asin(x)
+#define _ARCTAN(x) atan(x)
 #define _COS(x) cos(x)
 #define _EXP(x) exp(x)
 #define _GAME(x) (x)
@@ -33,6 +36,8 @@ extern "C" {
 #define _SIN(x) sin(x)
 #define _SQRT(x) sqrt(x)
 #define _STEP(height, step_time) (_time + _time_step / 2.0 > (step_time) ? (height) : 0.0)
+#define _TAN(x) tan(x)
+
 
 double* _ALLOCATE_AVAILABLE(double* requested_quantities, double* priority_profiles, double available_resource, size_t num_requesters);
 double _PULSE(double start, double width);