One possibility is to use external data module, if
you are using Workbench Mechanical.

https://www.youtube.com/watch?v=If145RMiLkY

Thank you, but I'm actually using MAPDL.
This is the plotted function in Wolfram Alpha.

Even though you are using MAPDL, L_K:s advice is sound, try it out at a model similar to the one you analyse in MAPDL, read the input file generated by Mechanical and tweak the generated APDL to do what you want. Or you can read the fine manual about tabular loads. Also this document will get help you started: http://www.padtinc.com/blog/what-every-user-should-know-about-tables-in-ansys-mechanical-apdl/

Got it! A friend helped me. This is the APDL command to apply bi-sinusoidal pressure on a square plate.

! Definição da tabela a partir da função.
*DEL,_FNCNAME
*DEL,_FNCMTID
*DEL,_FNCCSYS
*SET,_FNCNAME,'bisin'
*SET,_FNCCSYS,0
! /INPUT,bisinusoidal_1.func,,,1
*DIM,%_FNCNAME%,TABLE,6,14,1,,,,%_FNCCSYS%
!
! Begin of equation: -0.5*SIN(({PI}/1500)*{X})*SIN(({PI}/1500)*{Y})
*SET,%_FNCNAME%(0,0,1), 0.0, -999
*SET,%_FNCNAME%(2,0,1), 0.0
*SET,%_FNCNAME%(3,0,1), 0.0
*SET,%_FNCNAME%(4,0,1), 0.0
*SET,%_FNCNAME%(5,0,1), 0.0
*SET,%_FNCNAME%(6,0,1), 0.0
*SET,%_FNCNAME%(0,1,1), 1.0, -1, 0, 3.14159265358979312, 0, 0, 0
*SET,%_FNCNAME%(0,2,1), 0.0, -2, 0, 1500, 0, 0, -1
*SET,%_FNCNAME%(0,3,1), 0, -3, 0, 1, -1, 4, -2
*SET,%_FNCNAME%(0,4,1), 0.0, -1, 0, 1, -3, 3, 2
*SET,%_FNCNAME%(0,5,1), 0.0, -1, 9, 1, -1, 0, 0
*SET,%_FNCNAME%(0,6,1), 0.0, -2, 0, -0.5, 0, 0, -1
*SET,%_FNCNAME%(0,7,1), 0.0, -3, 0, 1, -2, 3, -1
*SET,%_FNCNAME%(0,8,1), 0.0, -1, 0, 3.14159265358979312, 0, 0, 0
*SET,%_FNCNAME%(0,9,1), 0.0, -2, 0, 1500, 0, 0, -1
*SET,%_FNCNAME%(0,10,1), 0.0, -4, 0, 1, -1, 4, -2
*SET,%_FNCNAME%(0,11,1), 0.0, -1, 0, 1, -4, 3, 3
*SET,%_FNCNAME%(0,12,1), 0.0, -1, 9, 1, -1, 0, 0
*SET,%_FNCNAME%(0,13,1), 0.0, -2, 0, 1, -3, 3, -1
*SET,%_FNCNAME%(0,14,1), 0.0, 99, 0, 1, -2, 0, 0
! End of equation: -0.5*SIN(({PI}/1500)*{X})*SIN(({PI}/1500)*{Y})
!-->

Here's an example how to read your particular function from a csv file using *tread. I included also the original excel file
and the apdl command file to read the data. Please let me know if it works as intended.

https://www.dropbox.com/s/6c3cxhfhw7slmgn/tread_te...