Daniel Lignon
91 articles published in Tangente
Math for everyoneN°205Apr 20, 2022When numerical methods provide the solution
Except when a differential equation is linear or of a very special type, there is generally no exact method for solving it—that is, for finding a solution. We therefore often have to resort to approximation methods and numerical schemes.
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Math for everyoneN°81Feb 16, 2022Norms on function spaces
The notion of distance can also be applied to functions
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Math for everyoneN°81Feb 15, 2022Surprising distances
The Euclidean distance in the plane is the one everyone knows: it tells us that the shortest path between two points is a straight line. But there are many others, often rather unusual. Some are downright surprising…
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Math for everyoneN°81Feb 14, 2022Coloring problems
How many colors are needed to color the plane so that no two points exactly 1 unit apart ever have the same color? Behind this apparently elementary question lies a problem that remains unsolved.
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Math for everyoneN°81Feb 14, 2022The center of France
What do we mean by "the" center of France?
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N°81Feb 06, 2022Editorial
"Distance makes everything infinitely more precious." Arthur C. Clarke, 2001: A Space Odyssey (Hutchinson, 1968).
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Math for everyoneN°203Dec 16, 2021Gold, yes... but metal too
Mathematics enthusiasts—and mathematicians themselves—have no shortage of imagination! Starting from the golden ratio, some have defined a family of numbers known as metallic means that share certain properties with the golden ratio.
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Math for everyoneN°203Dec 15, 2021Remarkable mathematical properties
At first glance, the golden ratio, despite its mythical name, is nothing exceptional mathematically: it is simply the positive solution of a quadratic equation. Much ado about nothing? Let's see, then, what surprises it has in store.
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Math for everyoneN°80Nov 18, 2021Lie groups
The groups introduced by mathematician Sophus Lie have become indispensable tools in theoretical physics.
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N°80Nov 18, 2021Editorial
"The concept of a group already exists in our minds, at least potentially. It forces itself upon us, not as a form of our sensibility, but as a form of our understanding." Henri Poincaré, La science et l'hypothèse, 1902.
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History and CultureN°80Nov 18, 2021The founders' group
The concept of a group did not simply appear overnight. Like many mathematical concepts, the idea took time—a great deal of time—to emerge, however "elementary" it may be, along with definitions… that now seem so obvious to us.
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Math for everyoneN°80Nov 18, 2021Groups: a matter of relationships
The concept of a group emerged in the early 19th century to solve polynomial equations and very quickly spread to other fields, including those outside mathematics: it allows us to focus on relationships between objects rather than on the objects themselves.
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