linear interpolation

[aliceman]

Hi,

i have to use linear interpolation in my program that's why
i chose this library to help me.

could anyone write me a few-line sample code with use of 
gsl_interp_linear declaration and gsl_interp_eval() function?
or, please, could anyone send me a link to the page with sample code?

when i tried to declare:
gsl_interp_linear *linear;
gsl_interp_accel *acc = gsl_interp_accel_alloc();

compiler said:
In function `main':
`linear' undeclared (first use in this function)
(Each undeclared indentifier is reported only once
for each function it appears in.)
parse error before `*'
`acc' undeclared (first use in this function)

included: 
#include <gsl/gsl_interp.h>

gsl verion:	gsl-1.1.1
system: 
	RH 7.2, kernel 2.4.18
gcc -v:		gcc version 2.96 20000731 (Red Hat Linux 7.1 2.96-98)

This is my first experience with this library,
but i cannot find enough examples to answer my question :(

aliceman