Code optimization tweaks from Norman Vine.

LaRCsim/atmos_62.c

@@ -89,7 +89,7 @@ void ls_atmos( SCALAR altitude, SCALAR * sigma, SCALAR * v_sound,
     int		index;
     SCALAR	daltp, daltn, daltp3, daltn3, density;
     SCALAR	t_amb_r, p_amb_r;
-    int         nonconstant_const_param = 5.256;
+    SCALAR      tmp;
 
     static SCALAR	d_a_table[MAX_ALT_INDEX][5] =
     {
@@ -254,7 +254,8 @@ void ls_atmos( SCALAR altitude, SCALAR * sigma, SCALAR * v_sound,
 	t_amb_r = 1. - 6.875e-6*altitude;
 	// printf("index = %d  t_amb_r = %.2f\n", index, t_amb_r);
 	// p_amb_r = pow( t_amb_r, 5.256 );
-	p_amb_r = pow( t_amb_r, nonconstant_const_param );
+	tmp = 5.256; // avoid a segfault (?)
+	p_amb_r = pow( t_amb_r, tmp );
 	// printf("p_amb_r = %.2f\n", p_amb_r);
       }
     else

LaRCsim/ls_accel.c

@@ -38,6 +38,9 @@
 	    
 $Header$
 $Log$
+Revision 1.4  1998/08/24 20:09:26  curt
+Code optimization tweaks from Norman Vine.
+
 Revision 1.3  1998/08/06 12:46:38  curt
 Header change.
 
@@ -102,6 +105,7 @@ void ls_accel( void ) {
   SCALAR	inv_Mass, inv_Radius;
   SCALAR	ixz2, c0, c1, c2, c3, c4, c5, c6, c7, c8, c9, c10;
   SCALAR	dx_pilot_from_cg, dy_pilot_from_cg, dz_pilot_from_cg;
+  SCALAR	tan_Lat_geocentric;
   
   
   /* Sum forces and moments at reference point */
@@ -132,12 +136,13 @@ void ls_accel( void ) {
   
   /* Calculate linear accelerations */
   
+  tan_Lat_geocentric = tan(Lat_geocentric);
   inv_Mass = 1/Mass;
   inv_Radius = 1/Radius_to_vehicle;
   V_dot_north = inv_Mass*F_north + 
-    inv_Radius*(V_north*V_down - V_east*V_east*tan(Lat_geocentric));
+    inv_Radius*(V_north*V_down - V_east*V_east*tan_Lat_geocentric);
   V_dot_east  = inv_Mass*F_east  + 
-    inv_Radius*(V_east*V_down + V_north*V_east*tan(Lat_geocentric));
+    inv_Radius*(V_east*V_down + V_north*V_east*tan_Lat_geocentric);
   V_dot_down  = inv_Mass*(F_down) + Gravity -
     inv_Radius*(V_north*V_north + V_east*V_east);
   
@@ -146,14 +151,16 @@ void ls_accel( void ) {
   ixz2 = I_xz*I_xz;
   c0  = 1/(I_xx*I_zz - ixz2);
   c1  = c0*((I_yy-I_zz)*I_zz - ixz2);
-  c2  = c0*I_xz*(I_xx - I_yy + I_zz);
-  c3  = c0*I_zz;
   c4  = c0*I_xz;
+  /* c2  = c0*I_xz*(I_xx - I_yy + I_zz); */
+  c2  = c4*(I_xx - I_yy + I_zz);
+  c3  = c0*I_zz;
   c7  = 1/I_yy;
   c5  = c7*(I_zz - I_xx);
   c6  = c7*I_xz;
   c8  = c0*((I_xx - I_yy)*I_xx + ixz2);
-  c9  = c0*I_xz*(I_yy - I_zz - I_xx);
+  /* c9  = c0*I_xz*(I_yy - I_zz - I_xx); */
+  c9  = c4*(I_yy - I_zz - I_xx);
   c10 = c0*I_xx;
   
   /* Calculate the rotational body axis accelerations */

LaRCsim/ls_aux.c

@@ -47,6 +47,9 @@
 
 $Header$
 $Log$
+Revision 1.4  1998/08/24 20:09:26  curt
+Code optimization tweaks from Norman Vine.
+
 Revision 1.3  1998/08/06 12:46:38  curt
 Header change.
 
@@ -140,6 +143,7 @@ void ls_aux( void ) {
 	/* SCALAR inv_radius_ratio; */
 	SCALAR	cos_rwy_hdg, sin_rwy_hdg;
 	SCALAR	mach2, temp_ratio, pres_ratio;
+	SCALAR  tmp;
 	
     /* update geodetic position */
 
@@ -261,7 +265,8 @@ void ls_aux( void ) {
 
 	mach2 = Mach_number*Mach_number;
 	temp_ratio = 1.0 + 0.2*mach2; 
-	pres_ratio = pow( temp_ratio, 3.5 );
+	tmp = 3.5;
+	pres_ratio = pow( temp_ratio, tmp );
 
 	Total_temperature = temp_ratio*Static_temperature;
 	Total_pressure    = pres_ratio*Static_pressure;

LaRCsim/ls_step.c

@@ -50,6 +50,9 @@
 
 $Header$
 $Log$
+Revision 1.4  1998/08/24 20:09:27  curt
+Code optimization tweaks from Norman Vine.
+
 Revision 1.3  1998/07/12 03:11:04  curt
 Removed some printf()'s.
 Fixed the autopilot integration so it should be able to update it's control
@@ -140,6 +143,7 @@ void ls_step( SCALAR dt, int Initialize ) {
 		SCALAR	e_dot_0, e_dot_1, e_dot_2, e_dot_3;
 	static	SCALAR	e_0, e_1, e_2, e_3;
 	static	SCALAR	e_dot_0_past, e_dot_1_past, e_dot_2_past, e_dot_3_past;
+	        SCALAR  cos_Lat_geocentric, inv_Radius_to_vehicle;
 
 /*  I N I T I A L I Z A T I O N   */
 
@@ -233,10 +237,14 @@ void ls_step( SCALAR dt, int Initialize ) {
     
 /* Calculate trajectory rate (geocentric coordinates) */
 
-    if (cos(Lat_geocentric) != 0)
+    inv_Radius_to_vehicle = 1.0/Radius_to_vehicle;
-    	Longitude_dot = V_east/(Radius_to_vehicle*cos(Lat_geocentric));
+    cos_Lat_geocentric = cos(Lat_geocentric);
+
+    if ( cos_Lat_geocentric != 0) {
+    	Longitude_dot = V_east/(Radius_to_vehicle*cos_Lat_geocentric);
+    }
     	
-    Latitude_dot = V_north/Radius_to_vehicle;
+    Latitude_dot = V_north*inv_Radius_to_vehicle;
     Radius_dot = -V_down;
     	
 /*  A N G U L A R   V E L O C I T I E S   A N D   P O S I T I O N S  */
@@ -255,9 +263,9 @@ void ls_step( SCALAR dt, int Initialize ) {
     
 /* Calculate local axis frame rates due to travel over curved earth */
 
-    P_local =  V_east/Radius_to_vehicle;
+    P_local =  V_east*inv_Radius_to_vehicle;
-    Q_local = -V_north/Radius_to_vehicle;
+    Q_local = -V_north*inv_Radius_to_vehicle;
-    R_local = -V_east*tan(Lat_geocentric)/Radius_to_vehicle;
+    R_local = -V_east*tan(Lat_geocentric)*inv_Radius_to_vehicle;
     
 /* Transform local axis frame rates to body axis rates */