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according to the text I am reading

a curve is geodesic if these conditions are met

##\frac{d}{ds}(2g_{mi} \frac{dx^{i}}{ds})-\frac{\partial g_{jk}}{\partial x^{m}}\frac{dx^{j}}{ds}\frac{dx^{k}}{ds} = 0##, where ##m=1,...,N##

a curve is a null geodesic if exactly the same conditions are met, just replace ##s## by ##\lambda## and call it an "affine parameter". It doesn't seem right...

On another forum someone had stated that as long as the above differential equations are solved, the curve resulting from them will be a null geodesic and the parameter will be an affine one.

Is this correct?