Loading source files of VSOP87 and calculating positions of the planet at given julian day. You should get VSOP87 solution files from VizieR archives.
http://cdsarc.u-strasbg.fr/viz-bin/Cat?cat=VI%2f81
vsop87.rb?f=FILE_NAME(&d=JULIAN_DAY)
if you omit param "d" you will get current position.
VizieR Online Data Catalog: Planetary Solutions VSOP87 (Bretagnon+, 1988)
http://adsabs.harvard.edu/abs/1995yCat.6081....0B
VizieR archives : Planetary Theories in rectangular and spherical variables: VSOP87 solution.
http://cdsarc.u-strasbg.fr/viz-bin/Cat?cat=VI%2f81
Copyright (c) 2017 Isana Kashiwai
Licensed under the MIT (MIT-LICENSE) license.