"SHADE.MTH: created by Peer van de Sanden; 01-01-1999"

F(x):=

G(x):=

space:=0.2

"internal functions"

MAXIMUM_F(a,b,space):=FLOOR(MAX(VECTOR(F(x),x,a,b,space))+2)

MAXIMUM_G(a,b,space):=FLOOR(MAX(VECTOR(G(x),x,a,b,space))+2)

MINIMUM_F(a,b,space):=FLOOR(MIN(VECTOR(F(x),x,a,b,space)))

MINIMUM_G(a,b,space):=FLOOR(MIN(VECTOR(G(x),x,a,b,space)))

SHADE_INTERNAL(a,b,i_):==IF(x>a,IF(b>x,MAX(MIN(x-i_,F(x)),G(x))))

SHADE_UNDER_INTERNAL(a,b,i_):==IF(x>a,IF(b>x,MAX(MIN(x-i_,G(x)),F(x))))

SHADE_BACK_INTERNAL(a,b,i_):==IF(x>a,IF(b>x,MAX(MIN(i_-x,F(x)),G(x))))

SHADE_BACK_UNDER_INTERNAL(a,b,i_):==IF(x>a,IF(b>x,MAX(MIN(i_-x,G(x)),F(x))))

"userfunctions"

SHADE(a,b,space):=VECTOR(SHADE_INTERNAL(a,b,i_),i_,a-MAXIMUM_F(a,b,space),b-M~
INIMUM_G(a,b,space),space)

SHADE_UNDER(a,b,space):=VECTOR(SHADE_UNDER_INTERNAL(a,b,i_),i_,a-MAXIMUM_G(a,~
b,space),b-MINIMUM_F(a,b,space),space)

SHADE_BACK(a,b,space):=VECTOR(SHADE_BACK_INTERNAL(a,b,i_),i_,a+MINIMUM_G(a,b,~
space),b+MAXIMUM_F(a,b,space),space)

SHADE_BACK_UNDER(a,b,space):=VECTOR(SHADE_BACK_UNDER_INTERNAL(a,b,i_),i_,a+MI~
NIMUM_F(a,b,space),b+MAXIMUM_G(a,b,space),space)