Roots of a function: Difference between revisions
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=={{header|REXX}}== |
=={{header|REXX}}== |
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===as-is function=== |
===as-is function=== |
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<lang rexx>/*REXX program |
<lang rexx>/*REXX program finds the roots of a specific function: x^3 - 3*x^2 + 2*x */ |
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parse arg bot top inc . /* |
parse arg bot top inc . /*obtain optional arguments from the CL*/ |
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if bot=='' | bot==',' then bot=-3 /*Not specified? Then use default*/ |
if bot=='' | bot==',' then bot=-3 /*Not specified? Then use the default.*/ |
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if top=='' | top==',' then top=+3 /* " " " " " */ |
if top=='' | top==',' then top=+3 /* " " " " " " */ |
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if inc=='' | inc==',' then inc=.0001 /* " " " " " */ |
if inc=='' | inc==',' then inc=.0001 /* " " " " " " */ |
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z=f(bot); !=sign(z) |
z=f(bot); !=sign(z) |
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do j=bot to top by inc /*traipse through |
do j=bot to top by inc /*traipse through the values specified.*/ |
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z=f(j); $=sign(z) /*compute new value and the sign.*/ |
z=f(j); $=sign(z) /*compute the new value and the sign.*/ |
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if z=0 then say 'found a root at' j/1 |
if z=0 then say 'found a root at' j/1 |
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else if !\==$ then if !\==0 then say 'passed a root at' j/1 |
else if !\==$ then if !\==0 then say 'passed a root at' j/1 |
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!=$ /*use the new sign |
!=$ /*use the new sign for the next time. */ |
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end /*j*/ |
end /*j*/ |
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exit /*stick a fork in it, we're done.*/ |
exit /*stick a fork in it, we're done.*/ |
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/*──────────────────────────────────F |
/*──────────────────────────────────F function────────────────────────────────*/ |
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f: procedure; parse arg x; return x**3 - 3 * x**2 + 2 * x</lang> |
f: procedure; parse arg x; return x**3 - 3 * x**2 + 2 * x</lang> |
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'''output''' when using the defaults for input: |
'''output''' when using the defaults for input: |
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<pre> |
<pre> |
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found a root at 0 |
found a root at 0 |
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