@Doug Meade 

dear Doug

thank you for your answer. i explain somthings:

f is a function of y.

becouse i have a physical problem so infinity can be 20 , and a can be 10 ,

so whit terms , f[infinity]=f[-infinity]=1 and f'[infinity]=f'[-infinity]=0 .

also phiB[y]=q*int(f,y=-infinity..y) , but i want plot q vs phiB[infinity] when phiB[infinity] change between 0..phi

@tomleslie 

dear tomleslie

thank you for your answer. i explain somthings:

f is a function of y.

becouse i have a physical problem so infinity can be 20 , and a can be 10 ,

so whit terms , f[infinity]=f[-infinity]=1 and f'[infinity]=f'[-infinity]=0 .

also phiB[y]=q*int(f,y=-infinity..y) , but i want plot q vs phiB[infinity] when phiB[infinity] change between 0..phi

@acer 

thank you.

@acer 

yes! you are rigth.

thank you for help, it works for me.

i cant speak english well! sorry

@Preben Alsholm 

thank you so much. it works for me

@Adri van der Meer 

thank you, but i want print just 1.81963128310659839.

@Markiyan Hirnyk 

i have a 2dplot. such that y:=(sin(x), x=0..Pi):

it have a maximum point. i want print size of y in maximum point that is 1. 

@Kitonum 

oh yes! i make a mistake.

thank you 

@Kitonum 

yes, thank you.

if i have a real numeric in my set, so what do i do?

i want first print real numeric, if no exist real numeric so do up way.

for example:

if A:= .5464691235-.4473247264*I, -.4563184747+1.*10^(-14)*I, .5464691235+.4473247264*I,0.9091925189

i want print 0.9091925189

if A:= .5464691235-.4473247264*I, -.4563184747+1.*10^(-14)*I, .5464691235+.4473247264*I

i want print  -.4563184747.

i cant spaek english well, sorry.

how can i find ya and yc finaly?

plz help.

@Axel Vogt 

i have solve  tow equatio together and contemporaneous.

so i know f and E are real and positive, and x is real too, and it can be one number bitween -3 ..3, like -1 or 2.

finaly i want to have ya and yc(my unknown).

@Preben Alsholm 

thank you

is y same y2?

yes, E and f are constants. and 0<ya<2.5 .

i want to plot ya vs. x and yc vs. x that -3<x<3.

@Kitonum 

thank you for your help

@tomleslie 

thank you for your help

@Kitonum 

i have a Matrix 8*12 and want deletion of columns 1,2,10,11

what about this?