thank you for taking the time to answer me. I learned one more thing!
However I can not figure out what I’d like to do well.
I click on a part of the screen, my character goes up this point by making a jump (done in two transitions)
I put the entire code below by replacing all my images by forms if you want to test and I notice that my xmiddle is negative while
zero the display starts well at the top left?
If you could shed some light my lantern on my mistake it would be nice 
thank you and good day.
local background=display.newRect( 0,200,4000,4000 ) local character = display.newCircle( 0,0,30 ) character.fill.effect = "filter.blur" local paint = {1, 0, 0} character.fill=paint local xbegin = 0 local ybegin = 200 character.yScale = 0.5 character.xScale = 0.5 character.x = xbegin character.y = ybegin print( xbegin, ybegin ) local function myTapListener(event) if event.x==xbegin then local xmiddle=event.x else local xmiddle=(event.x-xbegin)\*0.5+xbegin end if event.y==ybegin then local ymiddle=event.y else local ymiddle=(ybegin-event.y)\*0.5+ybegin end print( xmiddle, ymiddle ) print( event.x, event.y ) local xend = event.x local yend = event.y local function removal1(character) character:removeSelf() local character = nil end local function removal2(character) local character = display.newCircle( 0,0,30 ) character.fill.effect = "filter.blur" local paint = {1, 0, 0} character.fill=paint character.x = xmiddle character.y = ymiddle print (character.x) print( xend, yend ) local xbegin = xend local ybegin = yend print( xbegin, ybegin, xend, yend ) character:removeSelf() local character = nil local character = display.newCircle( 0,0,30 ) character.fill.effect = "filter.blur" local paint = {1, 0, 0} character.fill=paint character.x = xbegin character.y = ybegin character.yScale = 0.5 character.xScale = 0.5 return xbegin, ybegin, xend, yend end local transitionspecial = transition.to( character, { time=500, x=xmiddle, y=ymiddle, yScale=1, xScale=1, onComplete=removal1, transition=easing.inBounce }) local transitionspecial2= transition.to( character, { time=550, x=xend, y=yend, yScale=0.5, xScale=0.5, transition=easing.outElastic, onComplete=removal2 }) return xbegin, ybegin, xend, yend end background:addEventListener("tap", myTapListener )