### 5.21.24  Rewrite an expression with different options : convert convertir

convert takes two arguments an expression and an option.
convert rewrites this expression applying rules depending on the option. Valid options are :

• sin converts an expression like trigsin.
• cos converts an expression like trigcos.
• sincos converts an expression like sincos.
• trig converts an expression like sincos.
• tan converts an expression like halftan.
• exp converts an expression like trig2exp.
• ln converts an expression like trig2exp.
• expln converts an expression like trig2exp.
• string converts an expression into a string.
• matrix converts a list of lists into a matrix.
• polynom converts a Taylor series into a polynomial by removing the remainder (cf 5.25.22).
• parfrac or partfrac or fullparfrac converts a rational fraction into its partial fraction decomposition (5.29.9).

convert can also :

• convert units, for example convert(1000_g,_kg)=1.0_kg (cf 8.1.4).
• write a real as a continued fraction : convert(a,confrac,’fc’) writes a as a continued fraction stored in fc. Do not forget to quote the last argument if it was assigned.
For example, convert(1.2,confrac,’fc’)=[1,5] and fc contains the continued fraction equal to 1.2 (cf 5.8.7).
• transform an integer into the list of its digits in a base, beginning with the units digit (and reciprocally)
• convert(n,base,b) transforms the integer n into the list of its digits in base b beginning with the units digit.
For example, convert(123,base,10)=[3,2,1] and reciprocally
• convert(l,base,b) transforms the list l into the integer n which has l as list of its digits in base b beginning with the units digit.
For example, convert([3,2,1],base,10)=123 (cf 5.5).