Subversion Repositories wimsdev

!goto $wims_read_parm

:def

title=Plot line

synonyme=line plot, plot line of implicit equation, plot line by equation

input=equation

!exit

:proc

formula=!item 1 of $formula

fml=!mathsubst X=x in $fml

fml=!mathsubst Y=y in $fml

eq==

!if $eq isin $formula

 f=!translate internal = to , in $formula

 !distribute items $f into f1,f2

 !if $f2=$empty or $f1=$empty

  error=bad_formula

  !exit

 !endif

 fml=$f1 - ($f2)

!else

 !if y isvarof $formula

  fml=$formula

  formula=$formula = 0

 !else

  fml=$formula - y

  formula=y = $formula

 !endif

!endif

result=!exec pari eq=$fml; a=polcoeff(eq,1,x); print(a);\

	b=polcoeff(eq,1,y); print(b);\

	c=polcoeff(polcoeff(eq,0,x),0,y); print(c);\

	print(truncate(sqrt(a^2+b^2)));

result=!nonempty lines $result

!distribute lines $result into a,b,c,n

m=$[abs($c)/$n]

cnt=!linecnt $result

!ifval $cnt!=4 or $n=0 or NaN isin $m or Inf isin $m

 result=

 !exit

!endif

!if abs($a) > abs($b)

 px=$[$b]*t-($[$c/($a)])

 py=$[-($a)]*t

 ratio=$[abs($b)/abs($a)]

!else

 px=$[$b]*t

 py=$[-$a]*t-($[$c/($b)])

 ratio=$[abs($a)/abs($b)]

!endif

m=$[2*$m/max($ratio,0.15)^0.7]

!ifval $m=0

 m=5

!endif

!read insplot_set.proc

insplot_set=parametric; size $insplot_size; noborder;\

	arrow from -$m,0 to $m,0 lt 0;\

	arrow from 0,-$m to 0,$m lt 0;\

	xtics axis; ytics axis

!exit

:output

Line define by equation

!htmlmath $formula

 :

<p><center>

!insplot [-$m:$m] [-$m:$m] [-$m:$m] $px,$py notitle lt 1

</center>

!exit