TREE_X1 ¼ À45 {X location of the first tree with ripe fruit in the general
coordinate system for the designated space.}
TREE_X2 ¼ 45 {X coordinate of tree 2 in the designated space.}
TREE_Y ¼ IF TIME < 6 THEN TREE_Y1 ELSE IF TIME < 12 THEN TREE_Y2
ELSE 0
TREE_Y1 ¼ 90 {Y location of the first tree w/ripe fruit in the general coord. system
for the designated space.}
TREE_Y2 ¼ 90 {Y coordinate of tree 2 in the designated space.}
VISIBILITY ¼ IF TIME <¼16 THEN .1 ELSE 1 {Specified step rate for the troop.
2 meters per minute. Actual Tamarin data from P. Garber: 300 meter max.
distance or 86 minute max. travel time. Avg. travel time ¼ 26 min.}
WIND_ANGLE ¼ WIND_ANGLE_DEGREES * PI/180 {wind angle in radians,
counter-clockwise from + x axis.}
WIND_ANGLE_DEGREES ¼ -90 {Specified wind angle, degrees; counterclockwise from the + x axis, from the origin.}
WIND_SPEED ¼ 0.5
X1
¼
(XÀTREE_X1) * COS(WIND_ANGLE)
+
(YÀTREE_Y1) * SIN
(WIND_ANGLE) {The troop location coordinate, relative to tree 1, in terms
of the plume; X1 parallel to wind, Y1 perpendicular to X1.}
X2
¼
(XÀTREE_X2) * COS(WIND_ANGLE)
+
(YÀTREE_Y2) * SIN
(WIND_ANGLE) {The troop location coordinate, relative to tree 2, in terms
of the plume; X2 parallel to wind, Y2 perpendicular to X2.}
Y1 ¼ (Y À TREE_Y1) * COS(WIND_ANGLE) À (X À TREE_X1) * SIN
(WIND_ANGLE) {The troop location coordinate, relative to the tree 1, in
terms of the plume; X1 parallel to wind, Y1 perpendicular to X1.}
Y2 ¼ (YÀTREE_Y2) * COS(WIND_ANGLE) À (XÀTREE_X2) * SIN
(WIND_ANGLE) {The troop location coordinate, relative to tree 2, in terms
of the plume; X2 parallel to wind, Y2 perpendicular to X2.}
Δ_X1 ¼ XÀDELAY(X,1) {See note ΔY2.}
Δ_X2 ¼ DELAY(Δ_X1,1) {See note ΔY2.}
Δ_Y1 ¼ YÀDELAY(Y,1)
Δ_Y2 ¼ DELAY(Δ_Y1,1) {The Y location of the troop 2 steps ago. We now have
3 odor readings at 3 known locations. This forms a plane, the normal to which
gives us the local approximation of the direction of steepest ascent up the
odor hill.}
ΔCONC_1 ¼ CONCENTRATIONÀCONC_D1
ΔCONC_2 ¼ DELAY(ΔCONC_1,1)
Reference
1. Garber P, Hannon B (1993) Modeling monkeys: a comparison of computer generated and
empirical measures. Int J Primatol 14:827–852
Reference
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