STK_PLOT1D is a convenient plot function for 1D kriging predictions

 CALL: stk_plot1d (XI, ZI, XT, ZT, ZP)

    plots the evaluation points (XI, ZI), the "true function" with values
    ZT on the grid XT, and a representation of the prediction ZP on the
    same grid XT: the kriging prediction (posterior mean) surrounded by a
    shaded area corresponding to 95% pointwise confidence intervals.

    It is possible to omit plotting either the observations (XI, ZI) or
    the true function ZT by providing empty matrices.

 CALL: stk_plot1d (XI, ZI, XT, ZT, ZP, ZSIM)

    also plots a set ZSIM of samplepaths.

 CALL: stk_plot1d (H_AXES, ...)

    plots into existing axes with axis handle H_AXES.

 CALL: H_PLOT = stk_plot1d (...)

   returns the handles of the drawing in a structure.