     suivant: Number of zeros in monter: Arithmetic and polynomials précédent: Cyclotomic polynomial : cyclotomic   Table des matières   Index

## Sturm sequences and number of sign changes of P on ]a; b] : sturm

sturm takes two or four arguments : P a polynomial expression or P/Q a rational fraction and a variable name or P a polynomial expression, a variable name and two real or complex numbers a and b.

If sturm takes two arguments, sturm returns the list of the Sturm sequences and multiplicities of the square-free factors of P (or P/Q) (in this case sturm behaves like sturmseq).

If sturm takes four arguments, it behaves like sturmab :

• if a and b are reals, sturm returns the number of sign changes of P on ]ab]
• if a or b are complex, sturm returns the number of complex roots of P in the rectangle having a and b as opposite vertices.
Input :
sturm(2*x`^`3+2,x)
Output :
[2,[[1,0,0,1],[3,0,0],-9],1]
Input :
sturm((2*x`^`3+2)/(x+2),x)
Output :
[2,[[1,0,0,1],[3,0,0],-9],1,[[1,2],1]]
Input :
sturm(x`^`2*(x`^`3+2),x,-2,0)
Output :
1     suivant: Number of zeros in monter: Arithmetic and polynomials précédent: Cyclotomic polynomial : cyclotomic   Table des matières   Index
giac documentation written by Renée De Graeve and Bernard Parisse