32 lines
3.2 KiB
Rexx
32 lines
3.2 KiB
Rexx
/*REXX program calculates the distance between two points (2D) with error propagation. */
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parse arg a b . /*obtain arguments from the CL*/
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if a=='' | a=="," then a= '100±1.1, 50±1.2' /*Not given? Then use default.*/
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if b=='' | b=="," then b= '200±2.2, 100±2.3' /* " " " " " */
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parse var a ax ',' ay; parse var b bx ',' by /*obtain X,Y from A & B point.*/
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parse var ax ax '±' axe; parse var bx bx '±' bxE /* " err " Ax and Bx.*/
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parse var ay ay '±' aye; parse var by by '±' byE /* " " " Ay " By.*/
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if axE=='' then axE= 0; if bxE=="" then bxE= 0 /*No error? Then use default.*/
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if ayE=='' then ayE= 0; if byE=="" then byE= 0 /* " " " " " */
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say ' A point (x,y)= ' ax "±" axE', ' ay "±" ayE /*display A point (with err)*/
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say ' B point (x.y)= ' bx "±" bxE', ' by "±" byE /* " B " " " */
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say /*blank line for the eyeballs.*/
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dx= ax-bx; dxE= sqrt(axE**2 + bxE**2); xe= #(dx, 2, dxE) /*compute X distances (& err)*/
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dy= ay-by; dyE= sqrt(ayE**2 + byE**2); ye= #(dy, 2, dyE) /* " Y " " " */
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D= sqrt(dx**2 + dy**2) /*compute the 2D distance. */
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say 'distance=' D "±" #(D**2, .5, sqrt(xE**2 + yE**2)) /*display " " " */
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exit 0 /*stick a fork in it, we're all done. */
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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#: procedure; arg x,p,e; if p=.5 then z=1/sqrt(abs(x)); else z=abs(x)**(p-1); return p*e*z
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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sqrt: procedure; parse arg x; if x=0 then return 0; d=digits(); numeric digits; h=d+6
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numeric form; parse value format(x,2,1,,0) 'E0' with g "E" _ .; g=g * .5'e'_ % 2
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m.=9; do j=0 while h>9; m.j=h; h=h%2+1; end /*j*/
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do k=j+5 to 0 by -1; numeric digits m.k; g=(g+x/g)*.5; end /*k*/
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numeric digits d; return g/1
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/*──────────────────────────────────────────────────────────────────────────────────────*/
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sqrt: procedure; parse arg x; if x=0 then return 0; d=digits(); numeric digits; h=d+6
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numeric form; parse value format(x,2,1,,0) 'E0' with g "E" _ .; g= g * .5'e'_ % 2
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m.= 9; do j=0 while h>9; m.j= h; h= h%2+1; end /*j*/
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do k=j+5 to 0 by -1; numeric digits m.k; g= (g+x/g)*.5; end /*k*/
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numeric digits d; return g/1
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