Though this is not a big issue since I can convert the strings to double as I want IDL still tells me the following
IDL>corr=read_csv(dir+'writecsv_test.csv') IDL> help,corr ** Structure <a683f30>, 4 tags, length=1176, data length=1176, refs=1: FIELD1 DOUBLE Array[21] FIELD2 STRING Array[21] FIELD3 STRING Array[21] FIELD4 STRING Array[21] with the file generated by: a=collect(1:10); b=collect(0:0.1:2); c=zeros(1,1,10); c[1,1,:]=a; xx=b; xx_s=broadcast(+,a,b'); eps=broadcast(-,a,b'); omga=broadcast(*,xx_s,c); writedlm(dirname(@__FILE__)*"\\writecsv_test.csv",zip(xx_s[1,1:end],xx[1:end],eps[1,1:end],omega[10,1:end,1]),',')
