Calculating EigenValues with CLAPACK

Hi,
This may be a lame question but, can you help me about calculating
eigenvalues with CLAPACK?
I have tried a simple C code to accomplish this for a 4x4 symmetric
upper-triangle matrix:

1 2 3 4
x 5 6 7
x x 8 9
x x x 10

Here is my code:

float ap[]={1,2,3,4,5,6,7,8,9,10};
float d[4];
float e[3];
float tau[3];
long info;
long n=4;
long ldz=n; // When <n CLAPACK gives parameter error, otherwise VC++
gives Access Violation
float work=(2*n)-2;
ssptrd_("U",&n,ap,d,e,tau,&info);
printf("%d\n",info); // This step outputs 0
ssteqr_("V",&n,d,e,ap,&ldz,&work,&info);
printf("%d\n",info);

.

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