problem with CHAMP function

hello!

I would like to draw a vector velocity field. my program returns me results for x and y components of position vector for each of 640 particles and vx, vy components of velocity for each of 640 particles (the problem is from fluid mechanics).
i have tried the following piece of code:
x=[-0.1720490 -0.1487229 -0.1305250 -0.1145734 -0.0985839 -0.0839435 -0.0688476 -0.0544547 -0.0397398 -0.0254066];
y=[-0.9771022 -0.9786739 -0.9800474 -0.9809699 -0.9819347 -0.9828030 -0.9835949 -0.9842851 -0.9848132 -0.9851994];
vx=[-0.0865696 -0.0932412 0.0501032 0.0070481 0.0198802 -0.0129471 -0.0303309 -0.0561734 -0.0786280 -0.1039486 ];
vy=[-0.0283387 -0.0447400 -0.0706520 -0.0859012 -0.0924338 -0.1009400 -0.1058732 -0.1108179 -0.1144853 -0.1172428];

champ1(x, y, vx, vy);

but it is giving me back error:

champ1(x, y, vx, vy);
!--error 999
champ1: first and third arguments have incompatible dimensions
at line 8 of exec file called by :
exec("C:/Users/Vesy/AppData/Local/Temp/SCI_TMP_1232_/Untitled1.sce");
in execstr instruction called by :

what am I doing wrong? whole matrix contains 640 particles that I would like to draw, this is only test matrix with 10 entries. I think that either there is problem with matrix entries or maybe I should use another function?

thx for help :)