Texas Instruments TI-92+, Список советов

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(y-ya)/(yb-ya) → u
( 1 -t)*( 1 -u)*zaa+t*( 1 -u)*zba+t*u*zbb+( 1 -t)*u*zab
EndFunc
Note that the variable names have been changed to avoid conflict with built-in variables. The
equivalence is
xa == x
1
ya == y
1
zaa == z
1
zab == z
2
xb == x
2
yb == y
2
zba == z
3
zbb == z
4
The z-variables are named so it is easy to remember which z-variable goes with a particular (x,y) data
point. The second two characters of each z-variable indicate the corresponding x- and y-variables:
zaa = f(xa,ya) zab = f(xa,yb) zba = f(xb,ya) zbb = f(xb,yb)
As an example, given this data:
zbb = 0.5394 zba = 0.5534 xb = 0.6
zab = 0.4580 zaa = 0.4699 xa = 0.5
yb = 0.3 ya = 0.2
to interpolate for x = 0.52 and y = 0.28, the call is
bilinint(.5,.6,.2,.3,.4699,.4580,.5534,.5394,.58,.28)
which returns 0.4767.
This program, bilinui(), provides a user interface for the interpolation function.
bilinui()
Prgm
©User interface for bilinint()
©8oct00 dburkett@infinet.com
local z
if gettype(x 1 )="NONE" then
0 → xa:2 → xb:0 → ya:2 → yb
0 → zaa: 1→ zab:2 → zba:3 → zbb
1→ x: 1→ y
endif
lbl l 1
string(xa) → xa:string(xb) → xb
string(ya) → ya:string(yb) → yb
string(zaa) → zaa:string(zab) → zab
string(zba) → zba:string(zbb) → zbb
dialog
title "bilinui"
request "x 1 ",xa
request "x2",xb
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