@Kitonum i mean 1/(1-exp(a*x)*erfc(a*x))

@mehdi jafari i mean 1/(1-exp(a*x)*erfc(a*x))... 1/() kole ebarat hast

@mehdi jafari 

Thank u so much ,,, dastet dard nakone 

@Preben Alsholm 

@Preben Alsholm  i did as u said , but for odes i have errors !

@Markiyan Hirnyk 

links not working !

r is radial and is const.

@Carl Love 

thank u , how can i divide this data to smaller distances ?