Subversion Repositories wimsdev

!if $wims_read_parm!=slib_header

 !goto proc

!endif

slib_title=The bound of a real function of two variables within a 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