**Guido Grandi** was a Camaldolese monk who worked on geometry and hydraulics.

- Guido was not given that name when he was baptised, rather he was given the name Francesco Lodovico but changed his name to Guido when he entered the Order of the Camaldolese.
- Grandi was educated first by the priest Pietro Canneti (1659-1730) and then at the Jesuit college in Cremona.
- At this stage Saccheri was not interested in mathematics and there was no mathematics in the courses that Grandi studied.
- A monastery and hermitage formed one unit in this Order and Grandi studied at the monastery of Sant' Apollinare in Classe, Ravenna.
- The following year, Grandi became a teacher of philosophy and theology at the Camaldolese monastery of Santa Maria degli Angeli in Florence.
- Grandi published Geometrica divinatio Vivianeorum problematum Ⓣ(Geometric solutions of Viviani's problems) in 1699.
- Grandi was able to solve the problem using a modification of Cavalieri's infinitesimal methods.
- A review of Grandi's work in Acta eruditorum Ⓣ(Journal of the learned) in 1701 brought him recognition in Italy and in other countries.
- Having learnt much geometry, between 1699 and 1700 Grandi began to look at applications to optics, mechanics, astronomy.
- Having now shown a deep understanding of mathematics, Grandi began to teach mathematics at the monastery of Santa Maria degli Angeli.
- Also around this time, Grandi also began to correspond with Tommaso Ceva who was at the Jesuit college of Brera in Milan.
- Grandi was a vigorous correspondent, exchanging letters with many scientists and theologians.
- The Accademia Arcadia was a literary academy which was founded in Rome in 1690 to promote a more natural, simple poetic style and around 1700 Grandi attended this Academy.
- Poetry, especially Latin poetry, was a favourite with Grandi throughout his life.
- Grandi was offered a chair of mathematics in Rome but the Grand Duke Cosimo did not want to lose his star mathematician and in May 1700, the Grand Duke Cosimo offered Grandi a position of professor of philosophy at Pisa.
- Grandi chose to go to Pisa rather than to Rome.
- Grandi taught methods of the infinitesimal calculus from 1702 in private lessons he was giving; he was the first to do so in Italy.
- Grandi had studied Newton's fluxions and Leibniz's differentials and used both approaches although he favoured the approach by Leibniz.
- One of Grandi's results in the Quadratura Ⓣ(Quadrature) caused a lot of interest.
- Grandi gave the curve the name Scala, the scale curve, because it can serve as a measure of light intensity.
- Now although Grandi continued to study the latest developments in mathematics, he also undertook other projects.
- This work was the result of extensive research undertaken by Grandi.
- However, several scholars were unhappy with Grandi's treatment and he was forbidden to use the archives at Camaldoli.
- The Grand Duke Cosimo supported Grandi's publication of the Dissertationes and decided that he would move to protect him.
- He did not like Grandi's international fame and, in an attempt to discredit him, criticised his Quadratura.
- As a result, Grandi published a second edition in 1710 and this time he was allowed to include the comment that he had proved that God could create the word out of nothing.
- Marchetti then published an attack on this second edition in 1711 to which Grandi responded with Dialoghi ...
- In 1710, Grandi published De infinitis infinitorum, et infinite parvorum ordinibus disquisitio geometrica Ⓣ(A geometric account of an infinite number of infinite things and of infinitely small order) in which he thanked the Royal Society for electing him.
- In 1714 Grandi was appointed Professor of Mathematics at the University of Pisa, a position which became vacant on the death of Marchetti and, in the same year, Newton sent him a copy of the second edition of the Principia.
- One of the results for which Grandi is best known today is his definition of the rodonea curve.
- Rodonea is the Latin for rose and Grandi first defined these curves in December 1713 in a letter he wrote to Leibniz.
- However, Grandi wanted this work to be more widely read than just by scholars so, in 1729, he produced an Italian version of the work which contained additional explanations and proofs.
- He died about a week later and was buried in the monastery church in a tomb with a marble bust by the sculptor Giovanni Baratta (1670-1747) and an inscription by Father A Forzoni, one of Grandi's students.

Born 1 October 1671, Cremona (now Italy). Died 4 July 1742, Pisa (now Italy).

View full biography at MacTutor

Origin Italy

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive