Isqrt (integer square root) of X: Difference between revisions
add RPL
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73 49,221,735,352,184,872,959,961,855,190,338,177,606,846,542,622,561,400,857,262,407 7,015,820,362,023,593,956,150,476,655,802
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=={{header|RPL}}==
Because RPL can only handle unsigned integers, a light change has been made in the proposed algorithm,
{{works with|Halcyon Calc|4.2.7}}
{| class="wikitable"
! RPL code
! Comment
|-
|
≪
#1
'''WHILE''' DUP2 ≥ '''REPEAT'''
SL SL '''END'''
#0
'''WHILE''' OVER #1 > '''REPEAT'''
SWAP SR SR SWAP
DUP2 +
SWAP SR SWAP
'''IF''' 4 PICK SWAP DUP2 ≥ '''THEN'''
- 4 ROLL DROP ROT ROT
OVER +
'''ELSE''' DROP2 '''END'''
'''END''' ROT ROT DROP2
≫
´'''ISQRT'''’ STO
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'''ISQRT''' ''( #n -- #√n )''
q ◄── 1
perform while q <= x
q ◄── q * 4
z ◄── x
r ◄── 0
perform while q > 1
q ◄── q ÷ 4
u ◄── r + q
r ◄── r ÷ 2
if z >= u then do
z ◄── z - u
r ◄── r + q
remove u and copy of z from stack
end perform, clean stack
|}
{{in}}
<pre>
≪ { } 0 65 FOR n n R→B ISQRT B→R + NEXT ≫ EVAL
≪ {} #7 1 11 START DUP ISQRT ROT SWAP + SWAP 49 * NEXT DROP ≫ EVAL
</pre>
{{out}}
<pre>
2: { 0 1 1 1 2 2 2 2 2 3 3 3 3 3 3 3 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 8 8 }
1: { # 2d # 18d # 129d # 907d # 6352d # 44467d # 311269d # 2178889d # 15252229d # 106765608d # 747359260d }
</pre>
=={{header|Ruby}}==
Ruby already has [https://ruby-doc.org/core-2.7.0/Integer.html#method-c-sqrt Integer.sqrt], which results in the integer square root of a positive integer. It can be re-implemented as follows:
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