The book "Computational Science and Its Applications - ICCSA 2003" is a comprehensive collection of contributions presented at the International Conference on Computational Science and its Applications in 2003 in Montreal, Canada. It highlights the growing importance of computational science across various scientific disciplines, including aerospace, chemistry, geosciences, finance, mathematics, and physics. The conference brought together researchers and practitioners from mathematics and computer science, as well as from various application fields, to discuss advanced applications of computational methods. The contributions in this volume reflect the challenges and solutions arising from the use of supercomputing, parallel processing, and complex algorithms. The invited speakers at the conference addressed innovative numerical methods and the latest developments in computational science that push the boundaries of modern computing techniques and hardware.