version 1.25, 2003/01/22 18:52:47
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version 1.27, 2003/01/25 13:44:54
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Line 164 AUser CSP
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Line 164 AUser CSP
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\ switch into postpone state |
\ switch into postpone state |
['] postponer is parser state on ; immediate restrict |
['] postponer is parser state on ; immediate restrict |
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\ f.rdp |
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: push-right ( c-addr u1 u2 cfill -- ) |
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\ move string at c-addr u1 right by u2 chars (without exceeding |
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\ the original bound); fill the gap with cfill |
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>r over min dup >r rot dup >r ( u1 u2 c-addr R: cfill u2 c-addr ) |
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dup 2swap /string cmove> |
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r> r> r> fill ; |
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: f>buf-rdp-try { f: rf c-addr ur nd up um1 -- um2 } |
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\ um1 is the mantissa length to try, um2 is the actual mantissa length |
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c-addr ur um1 /string '0 fill |
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rf c-addr um1 represent if { nexp fsign } |
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nd nexp + up >= |
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ur nd - 1- dup { beforep } fsign + nexp 0 max >= and if |
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\ fixed-point notation |
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c-addr ur beforep nexp - dup { befored } '0 push-right |
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c-addr beforep 1- befored min dup { beforez } 0 max bl fill |
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fsign if |
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'- c-addr beforez 1- 0 max + c! |
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endif |
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c-addr ur beforep /string 1 '. push-right |
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nexp nd + |
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else \ exponential notation |
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c-addr ur 1 /string 1 '. push-right |
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fsign if |
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c-addr ur 1 '- push-right |
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endif |
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nexp 1- s>d tuck dabs <<# #s rot sign 'E hold #> { explen } |
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ur explen - 1- fsign + { mantlen } |
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mantlen 0< if \ exponent too large |
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drop c-addr ur '* fill |
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else |
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c-addr ur + 0 explen negate /string move |
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endif |
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#>> mantlen |
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endif |
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else \ inf or nan |
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if \ negative |
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c-addr ur 1 '- push-right |
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endif |
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drop ur |
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\ !! align in some way? |
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endif |
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1 max ur min ; |
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: f>buf-rdp ( rf c-addr ur nd up -- ) \ gforth |
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\G Convert @i{rf} into a string at @i{c-addr ur}. The conversion |
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\G rules and the meanings of @i{ur nd up} are the same as for |
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\G @code{f.rdp}. |
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\ first, get the mantissa length, then convert for real. The |
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\ mantissa length is wrong in a few cases because of different |
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\ rounding; In most cases this does not matter, because the |
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\ mantissa is shorter than expected and the final digits are 0; |
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\ but in a few cases the mantissa gets longer. Then it is |
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\ conceivable that you will see a result that is rounded too much. |
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\ However, I have not been able to construct an example where this |
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\ leads to an unexpected result. |
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swap 0 max swap 0 max |
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fdup 2over 2over 2 pick f>buf-rdp-try f>buf-rdp-try drop ; |
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: f>str-rdp ( rf ur +nd up -- c-addr ur ) \ gforth |
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\G Convert @i{rf} into a string at @i{c-addr ur}. The conversion |
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\G rules and the meanings of @i{ur +nd up} are the same as for |
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\G @code{f.rdp}. The result in in the pictured numeric output buffer |
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\G and will be destroyed by anything destroying that buffer. |
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rot holdptr @ 1- 0 rot negate /string ( rf +nd up c-addr ur ) |
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over holdbuf u< -&17 and throw |
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2tuck 2>r f>buf-rdp 2r> ; |
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: f.rdp ( rf ur +nd up -- ) \ gforth |
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\G Print float @i{rf} formatted. The total width of the output is |
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\G @i{nr}, the number of digits after the decimal point is @i{+nd}, |
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\G the minimum number of significant digits for fixed-point notation |
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\G is @i{up}. @code{Set-precision} has no effect on @code{f.rdp}. |
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\G Fixed-point notation is used if the number of siginicant digits |
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\G would be larger than @i{up} and if the number of digits before the |
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\G decimal point would fit. If fixed-point notation is not used, |
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\G exponential notation is used, and if that does not fit, asterisks |
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\G are printed. We recommend using @i{ur}>=7 to avoid the risk of |
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\G numbers not fitting at all. We recommend @i{ur}>=@i{up}+5 to avoid |
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\G cases where @code{f.rdp} switches to exponential notation because |
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\G fixed-point notation would have too few significant digits, yet |
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\G exponential notation offers fewer significant digits. We recomment |
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\G @i{ur}>=@i{nd}+2, if you want to have fixed-point notation for some |
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\G numbers. |
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f>str-rdp type ; |
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0 [if] |
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: testx ( rf ur nd up -- ) |
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'| emit f.rdp ; |
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: test ( -- ) |
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-0.123456789123456789e-20 |
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40 0 ?do |
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cr |
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fdup 7 3 1 testx |
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fdup 7 3 4 testx |
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fdup 7 3 0 testx |
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fdup 7 7 1 testx |
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fdup 7 5 1 testx |
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fdup 7 0 2 testx |
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fdup 5 2 1 testx |
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fdup 4 2 1 testx |
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fdup 18 8 5 testx |
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'| emit |
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10e f* |
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loop ; |
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[then] |