If you want to plot this as a function, you'll need to write out theQuote:> here is my function to be graphed:

> F(X) = (X^t * A * X)^2 // X^t denotes the transpose of X

> // ^2 denotes raise to the 2nd power

> X is a vector, A is a symmetric square matrix.

> For 2x2 A and X =(x, y) F(X) is a surface in 3-D.

> The x-axis has the x component of X and the y-axis the y

> component of X. The z-axis has the value F(X) which is a scalar.

> How can I graph something like that? What sort of entries the data

> file needs? I tried different things but nothing seems to work right!

equation in scalar form as F(x,y) = ... because gnuplot doesn't have

vector arithmatic built-in.

Of course, you could always define your own 2x2 vector functions for

gnuplot ...

If you want to prepare a data file, it should be in "grid" format, which

looks like this:

x00 y00 z00

x10 y10 z10

x20 y20 z20

. . .

xN0 yN0 zN0

[null line -- nothing except newline and/or return]

x01 y01 z01

x11 y11 z11

x21 y21 z21

. . .

xN1 yN1 zN1

[null line]

x02 y02 z02

x12 y12 z12

x22 y22 z22

. . .

xN2 yN2 zN2

and so on.