Yoshisuke Matsunaga

Japanese: 松永良弼 - まつながよしすけ

[raw]?
[Died] Enkyo 1 (1744)
A Japanese mathematician in the mid-Edo period. His maiden name was Terauchi, and he was commonly known as Heihachiro, Gonpei, and Yasuemon. He also had the names Higashioka, Tatsuchi, Tangenshi, Boshinsai, and Toumei. Born in Kurume, he went to Edo and studied under Araki Murahide, a disciple of Seki Takakazu. He organized and developed Takakazu's work, organized a system of Japanese mathematician called the Seki school, and was the first to receive the Seki school's two-level teaching (Araki Murahide was the first to receive it). During the time of his disciple Yamaji Nushiju, five levels of Seki school certification were established. Ryosuke developed the theory of circles and clarified the relationship between the chord, arrow, and arc of a circle. In other words, he obtained the series expansion of trigonometric functions. Although Takebe Katahiro had completed a table of trigonometric functions for each degree, Ryosuke created a table of tenths (one hundredth) and calculated an 11-digit real number table. This was his "Wari En Ten Ten Hyō" (Wari En Ten Ten Hyō) in 1736. He also wrote many other books, including "Hoen Sanjing," "Wei Lao Yosan," "Sanpo Shusei" (9 volumes), and "Sanpo Ruiju" (10 volumes). He was close friends with Yoshita Kurushima (?-1757), who solved the Ensaikyoku Hejutsu, and on his recommendation, he served Masaki Naito, the lord of Nobeoka Domain in Hyuga, as a mathematics instructor. By order of the lord, Yoshisuke changed the arithmetic method that had been called Kigen Seiho to Tenzanjutsu.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

[生]?
[没]延享1(1744)
江戸時代中期の和算家。旧姓寺内，通称を平八郎，権平，安右衛門といい，東岡，龍池，探玄子，葆真斎，東溟と号した。久留米に生れ，江戸に出て，関孝和の高弟荒木村英に学び，孝和の遺業を整理・発展させて，関流と称される和算の体系を組織し，関流宗統2伝 (荒木村英が初伝) についた。弟子の山路主住のときには，関流免許の5段階が制定された。良弼は，円理を発展させて円の弦，矢，弧背の関係を明らかにした。すなわち，三角関数の級数展開を得たのである。1度ごとの三角関数表は建部賢弘が完成していたが，彼は (百分の) 十分の表をつくり，11桁の真数表を計算した。元文1 (1736) 年の『割円十分標』がそれである。ほかに『方円算経』『緯老餘算』『算法集成』 (9巻) ，『算法類聚』 (10巻) など撰著が多い。円裁極背術を解いた久留島義太 (?～1757) との親交が厚く，彼の推挙により，算学師範として日向延岡藩主内藤政樹に仕えた。この藩主の命により，帰源整法といっていた算法を点竄術 (てんざんじゅつ) と良弼が改めたという。

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