8.24 Functions on direction (Pure C)

These functions change the data in some direction like differentiations, integrations and so on. The direction in which the change will applied is specified by the string parameter, which may contain ‘x’, ‘y’ or ‘z’ characters for 1-st, 2-nd and 3-d dimension correspondengly.

C function: void mgl_data_cumsum (HMDT dat, const char *dir)

Cumulative summation of the data in given direction or directions.

C function: void mgl_data_integral (HMDT dat, const char *dir)

Integrates (like cumulative summation) the data in given direction or directions.

C function: void mgl_data_diff (HMDT dat, const char *dir)

Differentiates the data in given direction or directions.

C function: void mgl_data_diff_par (HMDT dat, const HMDT x, const HMDTy, const HMDTz)

Differentiates the data specified parametrically in direction x with y, z=constant. Parameter z can be NULL that correspond to 2D case. Parametrical differentiation uses the formula (for 2D case): da/dx = (a_j*y_i-a_i*y_j)/(x_j*y_i-x_i*y_j) where a_i=da/di, a_j=da/dj denotes usual differentiation along 1st and 2nd dimensions. The similar formula is used for 3D case. Note, that you may change the order of arguments – for example, if you have 2D data a(i,j) which depend on coordinates {x(i,j), y(i,j)} then usual derivative along ‘x’ will be Diff(x,y); and usual derivative along ‘y’ will be Diff(y,x);.

C function: void mgl_data_diff2 (const char *dir)

Double-differentiates (like Laplace operator) the data in given direction.

C function: void mgl_data_swap (HMDT dat, const char *dir)

Swaps the left and right part of the data in given direction (useful for Fourier spectrum).

C function: void mgl_data_mirror (HMDT dat, const char *dir)

Mirror the left-to-right part of the data in given direction. Looks like change the value index i->n-i.

C function: void mgl_data_sew (HMDT dat, const char *dir, float da)

Remove value steps (like phase jumps after inverse trigonometric functions) with period da in given direction.

C function: void mgl_data_smooth (HMDT dat, int Type, float delt, const char *dira)

Smooths the data on specified direction or directions by method Type. Now 4 methods are supported: SMOOTH_NONE does nothing for delta=0 or approaches data to zero with the step delta, SMOOTH_LINE_3 linear averaging by 3 points, SMOOTH_LINE_5 linear averaging by 5 points, SMOOTH_QUAD_5 quadratic averaging by 5 points. Parameter delta forbids to change values of array more than delta from the original ones. String dirs specifies the dimensions which will be smoothed. It may contain characters: 'x' for 1st dimension, 'y' for 2nd dimension, 'z' for 3d dimension.

C function: void mgl_data_envelop (HMDT dat, char dir)

Find envelop for data values along direction dir.

C function: void mgl_data_norm_slice (HMDT dat, float v1, float v2, char dir, int keep_en, int sym)

Normalizes data slice-by-slice along direction dir the data in slices to range [v1,v2]. If flag sym=true then symmetrical interval [-max(|v1|,|v2|), max(|v1|,|v2|)] is used. If keep_en is set then maximal value of k-th slice will be limited by \sqrt{\sum a_ij(k)/\sum a_ij(0)}.

C function: void mgl_data_norm (HMDT dat, float v1=0, float v2=1, int sym=false, int dim=0)

Normalizes the data to range [v1,v2]. If flag sym=true then symmetrical interval [-max(|v1|,|v2|), max(|v1|,|v2|)] is used. Modification will be applied only for slices >=dim.