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Scilab Help >> Elementary Functions > Matrix generation > meshgrid

meshgrid

Create matrices or 3-D arrays from vectors replicated in 2 or 3 dimensions

Syntax

U = meshgrid(u)
[U, V] = meshgrid(u)
[X, Y] = meshgrid(x, y)
[X, Y, Z] = meshgrid(x, y, z)

Arguments

u, x, y, z
Vectors of any types, of lengths nu, nx, ny, nz.

U, V
Square matrices of size nu x nu

X, Y, Z
Matrices or hypermatrices of the same size [ny, nx] or [ny, nx, nz].

Description

meshgrid(..) builds matrices or 3-D hypermatrices by replicating input vectors along 2 or 3 dimensions.

To create arrays of size [nx, ny] instead of [ny, nx], or with more than 3 dimensions, please use ndgrid(x, y) or ndgrid(x, y, z,..).

Most of Scilab 2D or 3D graphical functions like champ(), grayplot(), Sgrayplot(), plot3d(), contour(), etc.. work with grids generated with ndgrid(), not from meshgrid(). Data computed on grids coming from meshgrid() will require being transposed (please see the example thereafter).

Examples

[X, Y] = meshgrid(0:2)
--> [X, Y] = meshgrid(0:2)
 X  =
   0.   1.   2.
   0.   1.   2.
   0.   1.   2.

 Y  =
   0.   0.   0.
   1.   1.   1.
   2.   2.   2.

[X, Y] = meshgrid(["a" "bc" "αβγδ"], [-3 5])
--> [X, Y] = meshgrid(["a" "bc" "αβγδ"], [-3 5])
 X  =
!a  bc  αβγδ  !
!a  bc  αβγδ  !

 Y  =
  -3.  -3.  -3.
   5.   5.   5.

Application to grids for graphics:

// Generating data
x = -1:0.1:1.7;
y = -1:0.1:1;
[X, Y] = meshgrid(x, y);
Z = sinc(2*%pi * X.*Y);

// Setting the graphic figure
clf
drawlater
gcf().color_map = parulacolormap(64);
gcf().axes_size = [650 530];

// Plotting
subplot(2,2,1)
Sgrayplot(x, y, Z')
title(["Sgrayplot(x, y, Z'' ) " "$←\;Z^t\; required$"], "fontsize",3)
isoview, colorbar

subplot(2,2,2)
plot3d(x, y, Z', -125,50)
gce().color_flag = 1;
title(["plot3d(x, y, Z'' ) " "$←\;Z^t\; required$"], "fontsize",3)
isoview

subplot(2,2,3)
champ(x,y,sin(2*X'),cos(2*Y'))
title(["champ(x, y, sin(X'' ),cos(Y'' ))" "$←\;X^t\;\;Y^t\; required$"], "fontsize",3)
isoview

subplot(2,2,4)
surf(X, Y, Z)
title("surf(X, Y, Z)", "fontsize",3)
isoview

gcf().children.tight_limits = ["on" "on" "on"];
drawnow

See also

  • ndgrid — build matrices or N-D arrays by replicating some template vectors
  • repmat — Replicate and tile an array
  • feval — multiple evaluation
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Last updated:
Tue Feb 25 08:49:19 CET 2020