Manipulating list in order to interpolate

[grduran12]

So I'm trying to create a program able to interpolate from a list of values (more like a matrix) where the left column correspond to the value A and the right column to the value F(A) and so on, then if I'm interest on the value F(B) knowing B the program should do a linear interpolation between F(A) and F(C), I'm not familiar with programming on RPL I'm used to visual so I hope you guys can give me some hints so I'll do it myself.

Additional info:
I've a HP50g
I'm writing my codes on HPuseredit 6

[RPL Calcs]

@ Paste in the HPUserEdit and send to emulator
@ "sigma" is the greek letter sigma (somatory); caracter number 133.

[@ A F(A) B F(B)
[ 1 03.3 10 05.1 ]
[ 3 09.2 20 10.2 ]
[ 5 15.1 30 15.3 ]
[ 7 21.2 40 20.1 ]
]
'sigmaDAT' STO
@ sigmaDAT is the variable that contains the current statistical matrix.

{
3. @ column number specifying the independent-variable: "B"
4. @ column number specifying the dependent-variable: "F(B)"
0. @ intercept
0. @ slope
LINFIT @ regression model
}
'sigmaPAR' STO

@ sigmaPAR is the variable that contains the current statistical parameter list.

LR @ Linear Regression command

@ You'll get in the stack:
@ Level 2: Intercept: .15
@ Level 1: Slope: .501

@ 'F(B)=0.15+0.501*B'

@ NOTE:
@ use real numbers in sigmaPAR, not integers. That is:
@ use { 3. 4. 0. 0. LINFIT } and not { 3 4 0 0 LINFIT }.

[RPL Calcs]

Perhaps the best option to estimate values is the Fit Data Input Form:
[Right-Shift] [STAT] (3.Fit data..) [PRED]

or, to access it from a program, use:
# 3A002h FLASHEVAL and then press [PRED]

!!!WARNING!!! !!!WARNING!!! !!!WARNING!!!

# 3A002h FLASHEVAL only 49 series (49G, 48GII, 49G+ e 50G).

To the 48G/GX/G+ use # B417Fh LIBEVAL and then [PRED]

SYSEVAL, LIBEVAL and FLASHEVAL can cause calculator memory crash.

Look entries in:
http://www.area48.com/48entries.html
http://www.hpcalc.org/details.php?id=3248

[RPL Calcs]

INTRP

Performs single or double interpolation among multiple table entries.
http://www.hpcalc.org/details.php?id=3144