CReSyPS means "Code Rennais de Synthèse de Populations Stellaires". This is a simple Stellar Population Synthesis Code written with the aim of determining core overshooting amount for Magellanic Clouds main sequence stars. CReSyPS is described in Cordier et al. (2002) (a preprint version is avalaible here).

We summarize here the main steps of the algorithm used by CReSyPS:

• STEP 1: a mass distribution is generated following the Salpeter's law.
• STEP 2: for each mass, an evolutionary track is interpolated within the grid calculated by the evolutionary code. On each track, models are selected every time step \Delta t, which is adjusted in order to yield a total number of stars equivalent to the observed one.
• STEP 3: consistently with the value of the binary rate <\beta>, objects are randomly selected to belong to a binary system and the magnitudes of these systems are calculated. Triple systems (and higher multiplicity systems) are neglected.
• STEP 4: distance modulus is added (and in the case of SMC a random ``depth'' inside the cloud) and synthetic photometric errors are attributed to magnitudes.
• STEP 5: we use a ``quality filter'': objects with too large photometric errors are rejected from the synthetic sample.
• STEP 6: color is calculated, reddening and extinction coefficient are applied. Concerning reddening, a gaussian distribution is applied around the mean value in order to simulate object-to-object variations.

• Requirement: a FORTRAN compiler like g77
• Download the gzipped archive: CReSyPS.tar.gz
• Untar and uncompress the file somewhere on your hard disk, you should get a directory called CReSyPS/
• Go in CReSyPS/
• Compile the program: make
• An executable CReSyPS/ should be now present in your directory

• Type ./CReSyPS ... and answer the questions: numbers of stars, distance modulus, etc
• Input files come with the sources:
• liste_BVageXc_Files.in
• M3.0_0.004_0.0.BVageXc
• M4.0_0.004_0.0.BVageXc
• M5.0_0.004_0.0.BVageXc
• M6.0_0.004_0.0.BVageXc
• M7.0_0.004_0.0.BVageXc
• M8.0_0.004_0.0.BVageXc
• M9.0_0.004_0.0.BVageXc
• M10.0_0.004_0.0.BVageXc
• M11.0_0.004_0.0.BVageXc
They correspond to evolutionary tracks calculated with a metallicity Z=0.004 (canonical for the SMC) no overshooting and mass values: 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, and 11.0.