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<div class="ChapSects" ><a href="chap2.html#X7E12358984CA3111" >2 <span class="Heading" >Float package</span ></a>
<div class="ContSect" ><span class="tocline" ><span class="nocss" > </span ><a href="chap2.html#X7B4092CA7ABB93B0" >2.1 <span class="Heading" >A sample run</span ></a>
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<h3>2 <span class="Heading" >Float package</span ></h3>
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<h4>2.1 <span class="Heading" >A sample run</span ></h4>
<p>The extended floating-point capabilities of <strong class="pkg" >GAP</strong > are installed by loading the package via <code class="code" >LoadPackage("float" );</code > and selecting new floating-point handlers via <code class="code" >SetFloats(MPFR)</code >, <code class="code" >SetFloats(MPFI)</code >, <code class="code" >SetFloats(MPC)</code > or<code class="code" >SetFloats(CXSC)</code >, depending on whether high-precision real, interval or complex arithmetic are desired, or whether a fast package containing all four real/complex element/interval arithmetic is desired:</p>
<div class="example" ><pre >
<span class="GAPprompt" >gap></span > <span class="GAPinput" >LoadPackage("float" );</span >
Loading FLOAT 0.7.0 ...
true
<span class="GAPprompt" >gap></span > <span class="GAPinput" >SetFloats(MPFR); # floating-point</span >
<span class="GAPprompt" >gap></span > <span class="GAPinput" >x := 4*Atan(1.0);</span >
.314159e1
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Sin(x);</span >
.169569e-30
<span class="GAPprompt" >gap></span > <span class="GAPinput" >SetFloats(MPFR,1000); # 1000 bits</span >
<span class="GAPprompt" >gap></span > <span class="GAPinput" >x := 4*Atan(1.0);</span >
.314159e1
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Sin(x);</span >
.125154e-300
<span class="GAPprompt" >gap></span > <span class="GAPinput" >String(x,300);</span >
".3141592653589793238462643383279502884197169399375105820974944592307816406286\
208998628034825342117067982148086513282306647093844609550582231725359408128481\
117450284102701938521105559644622948954930381964428810975665933446128475648233\
78678316527120190914564856692346034861045432664821339360726024914127e1"
gap>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >SetFloats(MPFI); # intervals</span >
<span class="GAPprompt" >gap></span > <span class="GAPinput" >x := 4*Atan(1.0);</span >
.314159e1(99)
<span class="GAPprompt" >gap></span > <span class="GAPinput" >AbsoluteDiameter(x); Sup (x); Inf(x);</span >
.100441e-29
.314159e1
.314159e1
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Sin(x);</span >
-.140815e-29(97)
<span class="GAPprompt" >gap></span > <span class="GAPinput" >0.0 in last;</span >
true
<span class="GAPprompt" >gap></span > <span class="GAPinput" >1.0; # exact representation</span >
.1e1(∞)
<span class="GAPprompt" >gap></span > <span class="GAPinput" >IncreaseInterval(last,0.001); # now only 8 significant bits</span >
.1e1(8)
<span class="GAPprompt" >gap></span > <span class="GAPinput" >IncreaseInterval(last,-0.002); # now becomes empty</span >
∅
<span class="GAPprompt" >gap></span > <span class="GAPinput" >r2 := Sqrt(2.0);</span >
.141421e1(99)
<span class="GAPprompt" >gap></span > <span class="GAPinput" >MinimalPolynomial(Rationals,r2);</span >
-2*x_1^2+1
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Cyc(r2);</span >
E(8)-E(8)^3
gap>
<span class="GAPprompt" >gap></span > <span class="GAPinput" >SetFloats(MPC); # complex numbers</span >
<span class="GAPprompt" >gap></span > <span class="GAPinput" >z := 5.0-1.0i;</span >
.5e1-.1e1i
<span class="GAPprompt" >gap></span > <span class="GAPinput" >(1+1.0i)*last^4*(239+1.0i);</span >
.228488e6
<span class="GAPprompt" >gap></span > <span class="GAPinput" >Exp(6.2835i);</span >
.1e1+.314693e-3i
</pre ></div >
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