Subversion Repositories wimsdev

!if $wims_read_parm!=slib_header
 !goto proc
!endif
slib_title=The bound of a real function of two variables within an rectangle [x1,x2],[y1,y2]
slib_parms=7\
,the function expression\
[x,y],the variable names\
0,x1\
1,x2\
0,y1\
1,y2\
50,number of cutting steps (<=1000)
slib_author=Bernadette Perrin-Riou
slib_out=min,max
slib_comment=This script computes the minimum and the maximum of a function\
 of two variables within a rectangle, in a very approximative way. Its main purpose is for\
 plotting uses.
 slib_example=x^2+sin(x*y)+exp(y^2),[x,y],0,3,-3,2,50
 
!exit

:proc
!distribute items $wims_read_parm into slib_fn,slib_var,slib_x1,slib_x2,slib_y1,slib_y2,slib_steps
slib_fn=!rawmath $slib_fn
slib_var=!declosing $slib_var
slib_var1=!item 1 of $slib_var
slib_var2=!item 2 of $slib_var
!default slib_var1=x
!default slib_var2=y
slib_x1=$[$slib_x1]
!if $slib_x1=$empty or $slib_x1 isitemof NaN,Inf
         slib_x1=0
!endif
slib_x2=$[$slib_x2]
!if $slib_x2=$empty or $slib_x2 isitemof NaN,Inf
         slib_x2=1
!endif
slib_y1=$[$slib_y1]
!if $slib_y1=$empty or $slib_y1 isitemof NaN,Inf
 slib_y1=0
!endif
slib_y2=$[$slib_y2]
!if $slib_y2=$empty or $slib_y2 isitemof NaN,Inf
 slib_x2=1
!endif
!bound slib_steps between integer 1 and 1000 default 50
!bound slib_steps2 between integer 1 and 1000 default 50
slib_step=$[($slib_x2-($slib_x1))/$slib_steps]
slib_step2=$[($slib_y2-($slib_y1))/$slib_steps]
slib_min=$empty
slib_max=$empty

!for slib_i=0 to $slib_steps
        slib_fxn=!mathsubst $slib_var1= $[$slib_x1+$slib_i*$slib_step] in $slib_fn
        slib_fxn=!replace item NaN by $ in $slib_fxn
        slib_vals=!values $slib_fxn for $slib_var2=$slib_y1 to $slib_y2 step $slib_step
        slib_vals=!replace item NaN by $ in $slib_vals
        slib_vals=!nonempty items $slib_vals
        !if $slib_i>1 
                slib_vals=!sort numeric items $slib_min,$slib_vals,$slib_max
        !else
                slib_vals=!sort numeric items $slib_vals
        !endif
        slib_vals=!trim $slib_vals
        slib_min=!item 1 of $slib_vals
        slib_max=!item -1 of $slib_vals
!next slib_i

slib_out=$slib_min,$slib_max