AN introduction to the concept and methods of calculus will be held in April in a course called ''Foundation Mathematics: Calculus of One Variable and Vector Quantities''. Organised by the Department of Science and Mathematics of the School of Professional and Continuing Education of the University of Hong Kong, the course can be regarded as a preparatory foundation for the study of other higher level mathematics and science courses. It is expected to be of use to candidates preparing for public examinations in mathematics. Topics include: limits; differential calculus; integral calculus; vector calculus; and application of the above mentioned. Participants are expected to have a Form Five level of mathematical knowledge. Lectures will be conducted in English and supplemented with Cantonese. The course starts on April 28, and will be held on every Thursday from 8 pm to 9.30 pm at Room LG107, K. K. Leung Building, HKU. The fee is $460. For more information, call 859-2417.